Refurbishing the Catalinas Norte Development

Refurbishing the Catalinas Norte Development Dealing with the Legacy of Modernity in Buenos Aires, Argentina

AA E+E Environment and Energy Studies Programme Architectural Association School of Architecture Graduate School MArch Sustainable Environmental Design Dissertation Project 2011 - 2013 Rodolfo Pedro Augspach February 2013.

MArch Sustainable Environmental Design 2011 - 2013

“...by using our intellect to understand our instincts - to design our buildings and our systems (and our politics) to make doing the right thing just a little more attractive and a little easier, and the wrong thing a little more difficult, we might just tip the balance towards a sustainable path.”

Architectural Association School of Architecture

Nick Baker (2011)

Architectural Association School of Architecture.

SED lecture : “People and Sustainability”

Abstract This investigation is a critical review of the tower typology, focusing on its impacts on the urban tissue and pedestrian comfort. It is set in the “Catalinas Norte” development. This is an 8 ha plot along the river bank, cut off from the city by the 60 metre wide Alem Avenue. Over the past 30 years, ten freestanding tall buildings were built on this plot occupying less than 20% of the site with complete disregard for the microclimatic and other effects on the remaining 80% of the area. The research conducted for this project looks into the effects of the additional three towers which are currently under construction on the site. Additionally, comparisons are drawn with the urban character and environmental attributes of the Spanish grid that characterises the adjoining urban tissue. The findings from these studies have informed the proposals for ways in which architectural design can help integrate, rather than segregate, social activities while also providing appropriate environmental conditions for these activities to develop within the urban context.

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Rodolfo Pedro Augspach

MArch Sustainable Environmental Design 2011 - 2013

Architectural Association School of Architecture

Authorship declaration form AA + Environmental & Energy Studies Programme Architectural Association School of Architecture Graduate School Programme: MArch Sustainable Environmental Design Submission: Dissertation Project 2011 - 2013 Title:

Dealing with the Legacy of Modernity in Buenos Aires Refurbishing the Catalinas Norte Development Number of Words 13012 words in the main text Student Name: Rodolfo Pedro Augspach Declaration: “I certify that the contents of this document are entirely my own and that any quotation or paraphrase from the published or unpublished work of other is duly acknowledged�

Signature:

Date: February 8th

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Rodolfo Pedro Augspach

MArch Sustainable Environmental Design 2011 - 2013

Architectural Association School of Architecture

Table of Contents Abstract I Authorship Declaration Form III Table of Contents V List of Figures

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List of Tables IX Acknowledgements Introduction

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1. Theoretical Background

1.1 Open spaces in the city. A brief historical review 2

1.2 The importance of outdoor spaces 2

1.3 Comfort in urban outdoor spaces 4 1.4 Research Hypothesis 7

2. Context

2.1 The city of Buenos Aires 10 2.2 The Spanish grid 10 2.3 The site 12

2.4 Identification of three time frames 16 2.5 Transit and statying activities 16 2.6 Climate analysis 17 2.7 Time frame analyses 20

3. Analytic Work

3.1 Outdoor thermal comfort 24 3.2 Pedestrian thermal comfort in the Spanish grid 34

4. Predesign Studies

4.1 Wind studies 42 4.2 Solar studies 44

5. Design proposal

5.1 Design brief 48 5.2 Establishment of the site 50

5.3 Structuring the ground floor 52 5.4 Density 54 5.5 Assessing the wind environment 58 5.6 Area of focus 60 5.7 Visual connections 62

5.8 Dealing with the wind at the pedestrian level 64

5.9 On site performance assessment 67 5.10 Discussion 87

Conclusion Bibliography Appendix V

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Rodolfo Pedro Augspach

MArch Sustainable Environmental Design 2011 - 2013

Architectural Association School of Architecture

List of Figures Introduction Figure 0.1: Global population, divided into urban and rural.

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1. Theoretical Background Figure 1.1: La ville Radieuse (Radiant City) proposed by Le Corubiser.

Figure 1.2: Transport related oil consumption per capita for different cities.

Figure 1.3: Fractal showing degrees of privacy.

Figure 1.4: Factors which influence comfort Figure 1.5: Relationship between Occurrence of activities and conditions outdoors Figure 1.6: Relationship between comfort bands and adaptive opportunities

2 3 3 4 4 5

2. Context Figure 2.1: Commuting daily patterns in Buenos Aires Figure 2.2: Satellite image showing the Spanish grid in the city of Buenos Aires, Argentina Figure 2.3: Satellite Image showing the chaotic pattern of Portuguese settlement of Salvador do Bahia, Brazil Figure 2.4: Key plan showing location of the site within the city of Buenos Aires Figure 2.5: Key plan showing progression of the city of Buenos Aires over the River Plate Figure 2.6: Plan showing land uses and transport systems within a 500 metre radius.

Figure 2.7: Photograph of the site as it is presently (2012) Figure 2.8: CGI showing the evolution of the site to the year 2015 Figure 2.9: Identification of the three time frames Figure 2.10: Relationship transit and staying activities Figure 2.11: Global solar radiation broken into direct and diffused Figure 2.12: Mean daily mean, mean daily maximum and minimum dry bulb air temperatures Figure 2.13: Sun trajectories for the Winter and summer solstice and Spring Equinox Figure 2.14: Temperature frequency along the year Figure 2.15: Wind rose overlaid the Buenos Aires City plan for the identified warm, mild and cool periods respectively.

Figure 2.16: Time frame breakdown Figure 2.17: Frequency of different air velocities for the different time frames in the different periods Figure 2.18: Frequency of different sky cover conditions for the different time frames in the different periods Figure 2.19: Frequency of intensity of the direct component of the solar radiation for the different time frames in the different periods

10 10 11 12 12 13 14 15 16 16 17 17 18 18 19 20 21 21 21

3. Analytic Work Figure 3.1: Parameter values for the different iterations ran.

Figure 3.2: Clothing values used for simulations for the different seasonal periods.

Figure 3.3: Adaptive thermal comfort equation and band for 90% acceptability with the three climatic periods marked.

Figure 3.4: Connection between PMV and PPD. Figure 3.5: Relationship between PMV, PET and adaptive thermal comfort.

Figure 3.6: Relation between PET and PMV simulation results for all iterations with 0.5 m/s for the hours within the morning of the mild period.

Figure 3.7: Methodology followed for calculating the formulas for the incidence of clo and metabolic rate upon PET. Figure 3.8: Graph showing effects of removing 0.1 clo for different PET results.

Figure 3.9: Graph showing effects of increasing metabolic rate by 20 Watts for different PET results.

Figure 3.10: Diagram showing simulation steps and methodology for calculating the comfort graphs Figure 3.11: Comfort graphs for the different periods of the different seasons.

Figure 3.12: Sequence for discerning the K difference with different degrees of solar and wind exposure Figure 3.13: Comfort graphs for the different periods of the different seasons.

Figure 3.14: Medium density model used in the simulations.

Figure 3.15: Canyon and corner Global horizontal solar radiation intensity according to the different time frames of the different periods.

24 25 26 26 27 27 28 29 29 30 31 32 33 34 35

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Figure 3.16: Percentage of hours exposed to direct horizontal solar radiation for the different periods in the canyons and corners of a North - south grid and a Northwest - Southeast grid.

Figure 3.17: Percentage of hours with direct solar radiation in the different canyons for the different periods.

Figure 3.18: Percentage of total Hours of direct solar radiation lost with density increase Figure 3.19: Sky view factors for North - South and Northwest - Southeast canyons of the medium density case Figure 3.20: Percentage of reduction in diffused solar radiation due to density increase for the different time frames.

Rodolfo Pedro Augspach

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4. Predesign Studies Figure 4.1: Wind rose for the whole year.

Figure 4.2: CFDs for the 3 predominant wind directions.

Figure 4.3: Sun path diagram with focused time frames highlighted.

Figure 4.4: Percentage of hours of direct sunlight for the “critical periods”.

42 43 44 45

5. Design Proposal Figure 5.1: Design brief and strategies to follow.

Figure 5.2: Floor area ratio for Spanish grid medium and high density, and the different scenarios on site.

Figure 5.3: Sky view factor with the highlighted period of focus.

Figure 5.4: Pedestrian flows on site with the changes for 2015 and the proposal.

Figure 5.5: Plan showing different activities on site and within a 5 minute walk radius (500 metres).

Figure 5.6: Programmatic proportions considering the project.

Figure 5.7: Programmatic breakdown of the project.

Figure 5.8: Densification strategy of the project.

Figure 5.9: CGI showing the insertion of the project in the city.

Figure 5.10: CGI of the project viewed from above with the sun path diagrams for 6 representative points.

Figure 5.11: CFD simulations for the predominant wind directions on site with proposal.

Figure 5.12: Comparison of protected and exposed areas with the three scenarios.

Figure 5.13: Key map showing area of focus.

Figure 5.14: Study of direct solar availability on site within the different time frames.

Figure 5.15: Plan of area of focus.

Figure 5.16: Sun path diagram for point “A”.

Figure 5.17: Sun path diagram for point “B”.

Figure 5.18: CFD simulations performed on the focused site before Intervention Figure 5.19: CGI showing pergola working as a wind barrier.

Figure 5.20: CFD simulations performed on the focused site after Intervention.

Figure 5.21: CGI showing visual connection between spaces where the building is lowest so as to mitigate wind effects.

Figure 5.22: CGI showing the vantage point for the following images on October 6th at 12:30.

Figure 5.23: CGI for a typical summer morning (December 21st).

Figure 5.24: CGI for a typical summer midday (December 21st).

Figure 5.25: CGI for a typical summer afternoon (December 21st).

Figure 5.26: CGI for a typical spring morning (September 21st).

Figure 5.27: CGI for a typical spring midday (September 21st).

Figure 5.28: CGI for a typical spring afternoon (September 21st).

Figure 5.29: CGI for a typical winter morning (June 21st).

Figure 5.30: CGI for a typical winter midday (June 21st).

Figure 5.31: CGI for a typical winter afternoon (June 21st).

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49 50 51 52 53 54 55 55 55 56 59 59 60 61 62 63 63 64 65 65 66 67 69 71 73 75 77 79 81 83 85

MArch Sustainable Environmental Design 2011 - 2013

Architectural Association School of Architecture

List of Tables 1. Theoretical Background Table 1.1: Common social distances

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2. Context Table 2.1: Climatic data for Buenos Aires (-34°36’ S, 58°22’ W), Argentina Table 2.2: Time frame analysis

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3. Analytic Work Table 3.1: Lower and upper limits of the adaptive thermal comfort band for the different periods.

Table 3.2: Impact of adaptive opportunities upon thermal comfort for the different time frames. (°K) Table 3.3: Direct horizontal solar radiation levels in relation to frequency of occurrence for the different periods Table 3.4: Percentage of hours of direct solar radiation in the different canyons for the different periods.

30 32 35 39

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Rodolfo Pedro Augspach

MArch Sustainable Environmental Design 2011 - 2013

Architectural Association School of Architecture

Acknowledgements I would like to express my gratitude to the Architectural Association School of Architecture for granting me the bursary which allowed me to undertake the course in Sustainable Environmental Design.

My most sincere thanks are due to the director of the course and my tutor throughout the whole master, Professor Simos Yannas, who has always found means to orient my research into the right direction.

I would also like to thank the entire SED staff for their vast knowledge: Paula Cadima, Rosa Schiano-Phan, Gustavo Brunelli, Jorge Rodriguez Alvarez and specially Klaus Bode and Joana Carla Soares Gonรงalves who have always managed to find time to discuss the project further.

Moreover, the priceless teachings offered by invited lecturers such as Professor Nick Baker are here duly acknowledged.

Furthermore, I would like to take this opportunity to express my gratitude to my previous teachers in the field of environmental design Professors Martin Evans and Silvia de Schiller.

I would also like to acknowledge my gratitude to my former teammates of whom I take invaluable lessons Joao Cotta Oliveira, Nikhil Deotarase and specially Meital Ben Dayan who has offered instrumental feedback on the current work.

In addition, I express my thanks to Humberto Mora, for his patience and always constructive criticism in Manfred Court. For the same reason I would like to acknowledge Tomas Swett who provided cunning insights over the time I spent in Windsor House.

Additionally, I would like to thank all of my classmates of the SED 2011-2013 course. This is not only for offering their constant feedback and support, but for the spirit of comradeship they helped create which have made this demanding year that much easier.

Building on this, I would like to acknowledge Paula Gobbi for making this time in London so special and for the constant source of motivation she inspired upon me.

Finally, I feel the strong need and desire to thank my whole family for the financial and emotional support without which this work would have surely not have been possible.

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Rodolfo Pedro Augspach

MArch Sustainable Environmental Design 2011 - 2013

Architectural Association School of Architecture

Introduction The accelerating rate at which individuals have chosen to move towards urban environments has reached a tipping point by the year 2010. This means that over 50% (50.6) of the world’s 6 billion people are living in metropolitan areas.

This process is far from slowing down, and in fact it is projected that by the year 2050, 70% (UN-Habitat, 2010) of the total 9 billion will live in cities (Figure 1.1) (Anon., 2012). Meaning that by then, there will be twice as many city inhabitants as there are today. This is reason enough for urban environments to be studied carefully.

It has been acknowledged that buildings have a great impact upon their immediate surroundings, however this relationship is reciprocal. Open spaces are categorized as the major component of the urban environment, directly affecting the performance of the buildings which border them (Littlefair, et al., 2000). However, although this is already a factor of key relevance, where the real potential of the spaces between buildings lie is in its capabilities to attract people. Interesting public environments where chance encounters may occur, structure the core for an approach on social sustainability, key aspect of every successful city.

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Rodolfo Pedro Augspach

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World population (billlions)

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Rural population Urban population

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Urban population

South America and Caribean

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1971

1981

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2011

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Figure 0.1: Global population, divided into urban and rural.

Source: After World bank data

Importance of outdoor spaces in the urban realm

At the beginning of the twentieth century, the free standing building was believed to be the answer to the dichotomy of density and public space availability that urbanism was facing. It was assumed that freeing ground space and allowing for solar access would result in successful outdoor spaces. However, the importance was placed on the symbolism architecture could provide with the towers, and not on the microclimates created by such typologies. As a consequence, the outdoor spaces created were not explored enough, and have been in most cases, neglected.

This investigation sets out to assess the problems created with these spaces and tap any potential they might have. As a context an area concentrated with towers in the city of Buenos Aires has been chosen.

As a driver for this study, the following questions will be addressed:

Research Questions

- What makes for a successful outdoor space?

- How can thermal comfort be achieved outdoors in the city of Buenos Aires?

- Which other parameters influence physiological comfort outdoors?

- How does the existing consolidated urban tissue perform?

- Which are the problems found on the selected site?

- How may these problems be reverted?

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MArch Sustainable Environmental Design 2011 - 2013

Methodology

Architectural Association School of Architecture

In order to answer these questions, it was identified that the first issue to be addressed was thermal comfort outdoors in the city of Buenos Aires.

For this assessment, Physiological Equivalent Temperature iterations have ben ran using the Rayman© tool to determine the effect of wind and solar radiation upon thermal comfort during the different seasons of the year and at different daily periods. The influential factors of other physiological comfort parameters have been addressed through different literature references.

Subsequently, as much of the consolidated urban fabric is composed of the Spanish grid it became a focus of study. This investigation was conducted in order to assess the thermal comfort possibilities the main city tissue offered.

Once the Spanish grid had been assessed, the focus was moved on to the chosen site. Again thermal comfort possibilities were evaluated. Additionally, the effect of 3 office towers which are to be built on site by the year 2015 has also been assessed.

All these studies have been carried out in order to understand which parameters are involved in influencing pedestrian flows. Ultimately the goal was to create comfortable conditions on site in order to encourage pedestrian activity.

However, it was consistently found in the literature that the most successful outdoor spaces did not meet one “optimal” comfort condition, but rather, offered several (Katzschner, et al., 2000). This acknowledges user adaptation such as moving from one place to the other to meet one’s comfort requirements. It is also argued that in some cases, having the mere knowledge that this is a possibility allows for enough adaptation. Nevertheless, although this is more than a relevant factor, the achievement of a robust outdoor space relies strongly on the buildings which border and generate the activities that happen around or even within them.

Structure

The first chapter of this dissertation will address in further detail the importance of outdoor urban spaces, unravelling physiological comfort issues and then tackling their social impact. It will also lay the foundations for the discussion on the poor environments caused by tall buildings.

In a subsequent chapter a brief overview of the city of Buenos Aires and the Spanish grid will be given as a prelude to the presentation of the site. Furthermore, three daily time periods are introduced as key drivers of this investigation. In addition, a study on pedestrian activity is offered.

Concluding the context, the climate data will be introduced and analysed.

This analysis will start from a breakdown into three climatic periods in order to better understand the parameters at play. Finally, the climatic conditions of the time frames introduced for the three periods will be assessed from an outdoor comfort perspective

Moreover, in a third chapter, the analytic work assessing pedestrian comfort will be explained along with the studies done on the Spanish grid.

A fourth chapter will present studies carried out on the site given alongside conclusions of its performance.

Finally, the lessons are listed and expressed in a design proposal which will be presented and tested at an urban scale and then again at a pedestrian scale. Proof of application of the lessons will be shown through simulation.

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1.

Theoretical Background

1.1 Open spaces in the city. A brief historical review 1.2 The importance of outdoor spaces 1.3 Comfort in urban outdoor spaces 1.4 Research Hypothesis

Chapter 1: Theoretical Background

Rodolfo Pedro Augspach

1.1 Open spaces in the city, a brief historical review

Urban sprawl

The tower typology

CIAM Athens Charter

Ever since the industrial revolution, urban life sprawled. Work opportunities and community life drew people into ever growing cities.

Very rapidly density became a problem as hygiene requirements were ignored. Already in the nineteenth century issues associated with density were identified, as Luke Howard made his pioneering investigations into the urban heat island (Howard, 1833). In addition, overly dense cities gave way to a lack of open spaces.

As the twentieth century dawned, the main concern of the urban planners and architects shifted towards designing for cities with air, light and sun. Concurrently, innovations in the building industry with wrought iron along with Ottis’ development of the elevator allowed for a new typology to emerge (Frampton, 1992).

As a consequence, in 1933, the CIAM “Athens Charter� sought out to solve the issues through a rigorous segregation of uses. In these master plans, the free standing building was adopted as the solution to all the problems urban planners had been facing. This zoning approach towards city planning resulted in metropolitan environments with a very high dependence upon the automobile, and strained the infrastructure.

Traffic flows became unidirectional, as people moved from where they lived to where they worked. Moreover, open spaces were now available as seen in Figure 2, but their overall performance was broadly overlooked.

Synergies between different activities were no longer possible, and city life quality dropped.

1.2 The importance of Outdoor spaces

The compact city and energy efficiency

It is argued that successful urban outdoor spaces are what give cities their vitality, structuring social inclusion within them. Over 50% of the world population live in cities. Moreover, it is suggested that compact cities have more cost effective supply and disposal infrastructure along with more efficient public transport systems (Rode & Burdett, 2012). Figure 1.2 shows transport related oil consumption per capita in relation to city density. Consequently, the link is established between energy efficiency and compact communities, making city life the most sustainable way of life we know.

Figure 1.1: La ville Radieuse (Radiant City) proposed by Le Corbusier.

Source: After Le Corbusier

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MArch Sustainable Environmental Design 2011 - 2013

Automobile city

Pedestrian city

Architectural Association School of Architecture

Nevertheless, city life happens in the streets. In an automobile oriented city, these streets are filled with cars, which contribute to pollution, heat, and generate traffic noise, hindering pedestrian comfort. In addition to the problems stated, and perhaps the most urgent one, is the socially divisive nature of these cities.

In the opposite case, pedestrian flow is predominant, movement is slowed down, and chance encounters may happen The human being is a social creature, and as such, it needs if at least passively, the possibility to see and hear others.

Open spaces may provide the setting for this interaction to happen, and when it doesn’t happen more dependency is placed upon entertainment systems (Gehl, 1987). It is further acknowledged that people are drawn by other people. As an old Scandinavian proverb illustrates: “People come where people are”

Outdoor spaces within cities

This constitutes a vicious circle, where activity generates more activity. Similarly, people don’t go, where there is no activity, unless they have to, resulting in dead spaces. One of the major benefits of generating pedestrian movement is the sense of community and security commonly associated with it.

In order to strengthen the sense of community it is vital that degrees of privacy exist, ultimately enabling individuals to move gradually from a private space to a public one, such as the one illustrated in the fractal of Figure 1.3. An example for this would be a progressive move from a bedroom, to a living room, subsequently to the front porch or balcony, and then to a public plaza or square. This not only gives people different choices for adaptive opportunities (see page 5), but also generates a sense of belonging. This sensation is explained by the fact that the “residential environment, can extend well beyond the actual dwelling” (Gehl, 1987).

Nevertheless, this sentiment ceases to exist in an under defined city structure, where the limit between public and private is blurred and not clearly demarcated (Jacobs, 1961)

Yearly oil consumption per capita (1000 L.)

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50

0

100

300

Population per hectare Figure 1.2: Transport related oil consumption per capita for different cities.

Figure 1.3: Fractal showing degrees of privacy.

Source: Newman and Kenworthy (1989)

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Chapter 1: Theoretical Background

Rodolfo Pedro Augspach

1.3 Comfort in urban outdoor spaces

The well-being of an individual is based on a number of influential factors. Comfort may therefore be subdivided into three categories, which may then again be broken down as shown in Figure 2.4. This breakdown will allow for better understanding of how to address the different issues and which order, so as to create a comfortable setting.

Comfort

Food intake

Age

Gender

Physical fitness

Physiological Conditions

Daily and annual rhythms

Adaptation acclimatization

Activity

Clothing

Intermediary Conditions

Olfactory

Visual

Acustic

Thermal

Physical Conditions

Figure 1.4: Factors which influence comfort Source: After Hegger et. al. (2008)

It is essential to create a comfortable outdoors environment as it may allow for activities to develop in open spaces. Several authors agree that outdoor comfort expectancy is not as high as indoors. Therefore, it may be stated that people will readily accept conditions that they would find uncomfortable in an interior environment. This is markedly true when other influential factors come into play, such as good views, pedestrian movement, or activity development, etc.

The relevance of thermal comfort outdoors

However, although this adaptation is broadly recognized, in the majority of situations, the decision to stay outdoors or move indoors is made in a split second when available. Therefore, it is important that highly comfortable conditions are provided in order to encourage people to choose the latter. In addition, the scheme in Figure 2.5 shows the relationship between the quality of the physical environment and the rate of occurrence of outdoor activities.

Outdoor setting Poor conditions

Good conditions

Necessary activities

Optional activities

Social activities Figure 1.5: Relationship between Occurrence of activities and conditions outdoors Source: Gehl (2009)

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MArch Sustainable Environmental Design 2011 - 2013

The need for providing different microclimates

Architectural Association School of Architecture

Nevertheless, recent studies have shown that places which offer a wide variety of microclimates within a short walkable distance are found more agreeable for subjects in terms of thermal comfort (Katzschner, et al., 2000) (Nikolopoulou, 2002). This may be explained by applying the adaptive comfort theory. As explained by Baker: “Adaptive actions, and the interpretation of long term situation, are then, a key factor in satisfaction with the environment. It follows that a vital quality of an environment is the opportunity to make adaptive actions (Baker, 2008).”

stimulus

Adaptive thermal comfort

Figure 1.6 shows an inverse relationship between offer of adaptive opportunities and thermal stress. Alternatively, it also illustrates that when there is no possibility for adaptation (c), any deviation from the neutral zone will result in stress. This last scenario is typically found in a comfort chamber, where Fanger conducted his investigations on thermal comfort (Fanger, 1970). The outcome of these investigations was his thermal balance equation, which relates to comfort through the predicted mean vote (PMV).

Adaptive opportunity

(a) good

Stress

(b) poor

(c) zero time

Figure 1.6: Relationship between comfort bands and adaptive opportunities.

Source: Baker (2008)

Originally this equation was formulated for indoor environments.

Nevertheless, it was gradually used to assess outdoor comfort. However, because of the issues presented above, several authors (Baker, 2008) (Nicol & Humphreys, 2002) argue that this method greatly underestimates subjects’ capabilities for adaptation, even for indoors. The core of this argument lies in results from field studies done in the tropics which revealed that people were not under thermal stress in conditions the model predicted they would be (de Dear, et al., 1997).

Problems with PMV and the use of PET

Moreover, for the reasons here presented PMV will not be used in this investigation to determine thermal stress outdoors. However, it will be used to assess the degree of the effect of adding or removing clothing or changing one’s metabolic rate. Consequently, physiological equivalent temperature (PET) calculations will be used to simulate pedestrian thermal comfort. The advantage of using this formula is that it enables an effective direct comparison with an indoor setting (Höpe, 1998).

Furthermore, for all purposes and references to comfortable indoor air temperatures, a comfort band will be calculated using the adaptive comfort equation proposed by De Dear and taught in the March/ Msc programme of Environmental Energy Studies at the Architectural Association (see page

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Chapter 1: Theoretical Background

Rodolfo Pedro Augspach

Thus far, thermal comfort has been addressed, but as discussed previously, other parameters affect the well-being of an individual. Visual stimulation is one of the influential factors which may allow for people to cope with conditions they would otherwise find unfitting. The same is true for adverse situations, where glare or poor lighting may increase the sensation of discomfort.

Daylight

Glare

In the urban realm, the lighting environment is strongly linked to the sky conditions, predominantly over orientation. This is so because daylight, as it is technically known, is the diffused light component which is emanated from the whole hemisphere (Szokolay, 2008). However, orientation does play a secondary role as the amount of light emanated from different parts of the hemisphere vary, and these variations are particular for each location of the globe (Baker & Steemers, 2002).

Nevertheless, studies show, that due to the high level of adaptation of the human eye, visual discomfort during the daytime in outdoor spaces is seldom related to low light levels, but rather, to strong contrasts producing glare (Nikolopoulou, 2002). Glare happens with more frequency on bright sunny days, as shaded areas contrast with exposed ones.

Another phenomenon frequently encountered in outdoor open spaces is saturation glare. This occurs when the average luminance of the field of vision is in excess of 80.000 apostilb (asb.) It can be seen to happen when a surface with high albedo (0.8 < Ď ) is hit by direct sun light (100.000 lx) giving as a result 80.000 asb.

Since daylight is related to the whole hemisphere, itâ&#x20AC;&#x2122;s availability at any particular point will be reduced in proportion to the amount of sky which is obstructed. Therefore, a link between daylight availability and confinement is established. This confinement at any one single point may be measured by calculating the sky view factor.

Sky view Factor

Oke has found that the sky view factor is also a measure of the intensity of the heat island effect (Oke, 1982). This link is stronger or weaker depending on other parameters such as wind, albedo (Taha, 1997), or orientation.

However, confinement is perhaps the most sensitive issue to address when designing public open spaces. This is mainly due to the fact that when a space is too enclosed lighting is hindered, and possibilities of escape, commonly restricted, leading an individual to feel unsafe (Littlefair, et al., 2000). When the opposite happens spaces become too impersonal and activities within them never develop as they get lost in space and time (Gehl, 2010). Table 1.1 shows an array of common social distances that must be borne in mind when determining the size of a public space, ranging from short, medium and long distances.

Table 1.1: Common social distances

Source: After Gehl (2008) and Littlefair et. al. (2000)

Long

Medium

Short

Distance (m) Notes

6

0.5 - 1.25 Maximum distance for touching 2.1 - 3.6 Conversation distance 12 Maximum distance to perceive facial expressions 20 - 24 Moods and feelings may be perceived 25 - 30 Hair style, facial features and age may be identified 70 - 100 Possible to discern another persons gender 100 - 135 Maximum distance for seeing any human movement

MArch Sustainable Environmental Design 2011 - 2013

Architectural Association School of Architecture

1.4 Research hypothesis This dissertation argues the following: “It is possible through sensible planning to integrate neglected city spaces with a robust urban tissue consolidating a resilient metropolitan environment.”

The terms articulating the hypothesis are hereby explained: - “sensible planning” refers to an intricate understanding of social patterns and behaviours coupled with a profound comprehension of the environmental conditions on site.

- integrate neglected city spaces” implies that underused pockets in cities as a consequence of poor planning may be revitalised in order to be positively mixed with the rest of the city.

- “robust urban tissue” is one that can endure the changes of a growing city without compromising the well-being of citizens, natural, or economic resources. Whilst at the same time addressing issues of social inequalities.

- “resilient metropolitan environment” alludes to an energy efficient city with a high rate of social inclusion, and a wide mix of activities offered.

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2.

Context

2.1 The city of Buenos Aires 2.2 The Spanish grid 2.3 The site 2.4 Identification of three time frames 2.5 Transit and statying activities 2.6 Climate analysis 2.7 Time frame analyses

Chapter 2: Context

Rodolfo Pedro Augspach

2.1. The city of Buenos Aires Buenos Aires is the capital city of Argentina and is the second biggest city in South America in terms of population, second only to Sao Paulo.

Within its metropolitan area of 48000 km² 13 million inhabitants reside.

This is more than 25% of the total population of Argentina. However, the inner city area which entails little over 200 km² consists of a population of 3 million. Nevertheless, as shown in the key plan of Figure 2.1, 1 million commuters make their way into the city through public transport and another 1.5 do so through private means on a daily basis (Garcia Espil, 1998).

Figure 2.1: Comutting daily patterns in Buenos Aires (thousands) Source: After Garcia Espil (1998)

2.2. The Spanish Grid Like for all cities founded by the Spanish, when Buenos Aires was founded, there was a strong and rigid set of guidelines to be followed. The main purpose of these guidelines, known as the “Indies laws” (ley de indias), was to facilitate governance. Every city being laid out the same, made it easier for visiting soldiers not to get lost.

Consequently, this is the reason why nowadays, Buenos Aires has the rigid urban pattern shown in the satellite image of Figure 2.2. This has a very strong contrast with Portuguese settlements, which did not have such guidelines. The satellite image of the Brazilian city of Salvador do Bahia in Figure 2.3 revealing its chaotic pattern illustrates this.

Additionally, the development in an orthogonal fashion was further encouraged by the lack of hills and natural accidents the site presented.

Moreover, plot sizes and street widths were set independent of site and climate, along with the location of the main governmental buildings. In addition, the axis of the grid is normal to the River Plate (Rio de la Plata) which is to the east of the city. As a result, most of it has been laid out following a North-South Axis.

Streets were originally 9.5 metres wide, but an ordinance in 1821 widened them to 13.4 metres in order to allow for sun and light.

Subsequently, in 1875 streets were yet again widened to the current average of 17.6 m.

The blocks which were about the size of a hectare, were subsequently broken down into several lots per street. This subdivision resulted in lots which have an average frontage width of 8.66 metres.

Figure 2.2: Satellite Image showing the spanish grid in the city of Buenos Aires, Argentina Source: After googlemaps.com

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Advantages

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The narrow width of the plots correlates to an issue that Ghel (1987) addresses when suggesting a strong proportional relationship between number of entrances per street and active city life. Bentley et al. (1985) refer to this as the urban quality of vitality, and it is essential for achieving pedestrian movement.

The strong orthogonal manner of the urban pattern of the city which has aided Spanish soldiers in the past is recognized as a positive aspect in terms of its legibility (de Schiller, 2004). This can be recognized in the behaviour of the citizens as people relate to distances through physical measurements (eg.: 100m). Unlike in more chaotic city patterns of medieval settlements where distances are referred to through time (eg.: 5 minute walk).

Disadvantages

However, the legibility which has been characterized as a positive aspect has also a very strong negative side to it. The lack of variety of block shape and size does not allow for sufficient flexibility. Thus, all of the city programmes have to be accommodated to the block as a common denominator or a module. When the need to build bigger structures than a block appears, connection problems and traffic issues quickly emerge, as a result of joining these modules. Additionally if all blocks and streets are the same shape and size then the sequence of space is lost resulting in monotony (Littlefair, et al., 2000).

Moreover, a problem that has been perceived with the grid has to do with the strictness of the street frontages and the nature of the narrow pavement area. This constitutes a very strong limit between the built and the un-built environment, which follows the nature of the grid which greatly limits the potential for sidewalk cafes. Hence, the possibility for people to participate of the urban scene when stopping for coffee or a meal is restricted. It is not to say that restaurants and cafes do not have outdoor areas, because it is not uncommon for them to have private gardens.

Nevertheless, the vitality, product of coupling pedestrians with people sitting down is lost. This problem dissolves in less dense areas of the city, where pavements are wider and the possibility of placing seats and tables exist, and it completely disappears in pedestrian streets.

Conclusion

Concluding, the Spanish grid has very strong positive aspects, allowing for life to happen upon the streets contributing to a vibrant city environment. This results from limited street and lot width, which contributes to the creation of a vibrant urban environment. However, identifying the problems it presents is fundamental for encouraging more pedestrian activity.

Figure 2.3: Satellite Image showing the chaotic pattern of Portuguese settlement of Salvador do Bahia, Brazil Source: After googlemaps.com

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Chapter 2: Context

Rodolfo Pedro Augspach

3.3 The Site City expansion

The sediments carried by the River Plate allowed for a yearly expansion of the city. Consequently, on the second half of the 20th century, urbanization plans for this new land were being considered. This new land was located to the east of the city as one can see in the location plan in Figure 2.4. Simultaneously, the ideas of the CIAM Athens charter were receiving momentum in Europe, and were strongly influencing South American urban planners.

As a result, the Catalinas Norte area, an eight hectare site was developed under these concepts. At present day it accommodates nine free standing office buildings and a hotel. It held no considerations towards the pedestrian in its planning, clearly constituting a neglected city space.

Therefore, it was concluded that this site provided the perfect setting to test the hypothesis presented previously.

Consolidated city grid

Figure 2.4: Key plan showing location of the site within the city of Buenos Aires

First expansion of the city over the sediments

Current land expansion due to sediments

Figure 2.5: Key plan showing progression of the city of Buenos Aires over the River Plate Source: After googlemaps.com

Source: After googlemaps.com

Variety

Connectivity

12

The key map (Figure 2.6) shows the different land uses found in its 500 metre radius. It may be detected that there is an existing mix of uses on the consolidated urban tissue whilst on site no such variety can be seen. Being all office buildings another problem emerges and it is linked to the working hours. Most office hours are from Monday to Friday from 10:00 to 18:00. Therefore, late in the day or during the weekends the site is deserted. This does not only make for a depressing site, but the lack of pedestrian presence in such a large area consolidates a pocket of insecurity.

Moreover, the site has the advantage of being very well connected to the existing public transport network. The bus and train terminal â&#x20AC;&#x153;Retiroâ&#x20AC;? is one of the biggest nodes of the city and concentrates an average of 320.000 commuters per day. In addtion, there is a very strong presence of pedestrian streets within the area. Another problem may be read with the cycling route which has been made to go through the back of the site, where no activity other than car traffic is registered. As a result, this cycling route is not used at all.

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Pedestrian Streets Bike Path Underground system Train Station Hotels Gastronomy Grocery Stores Shopping Centres Catalinas Norte development

Theaters Private Education Public Education Office towers on site

Figure 2.6: Plan showing land uses and transport systems within a 500 metre radius.

City structure

Motorway

These buildings occupy little under 20% of the total site. Upon the remaining 80% there are a few smaller buildings and mainly unconsolidated open space. This makes for an under defined city structure which presents a problem on its own. As no limit is placed between private and public domain entire areas are left unattended.

In addition, it is segregated from the city by 60 metre wide Alem Avenue (â&#x20AC;&#x153;Avenida Alemâ&#x20AC;?). This motorway makes conditions very difficult for pedestrians to cross, making the site work effectively like an island, where it is only traversable, at very specific locations. Additional problems identified with the avenue are noise and air pollution which hinder pedestrian comfort.

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Chapter 2: Context

Conclusions

Rodolfo Pedro Augspach

The photograph in Figure 2.7 shows the current state of the site.

The presence of the towers creates a very strong identity consolidating the river front. However, the lack of programmatic variety, along with the presence of the avenue has effectively limited the pedestrian movement upon the site. A recent study surveying pedestrian activity has revealed that actual pedestrian flow on site is one half the one encountered on the other side of the avenue (de Schiller, 2004).

Presently there are three towers being developed on site which will be completed by the year 2015. These are shown in the computer generated image of Figure 2.8. However, the effects these towers have on site are discussed in chapter 5, as a comparison to the design proposal.

Diagnosis of the Site: - Good connection to existing public transport network - Lack of programmatic variety - Lack of clear city structure - Hindered pedestrian activity due to the existence of 60 metre wide Avenue.

Figure 2.7: Photograph of the site as it is presently (2012)

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Figure 2.8: CGI showing the evolution of the site to the year 2015

15

Chapter 2: Context

Rodolfo Pedro Augspach

2.4 Identification of three time frames It has been identified by a recent study (Kampschroer, 2010) that Americans spend 90% of their time indoors. There is no similar research for the context under study, but up to an extent, this could also relate to the typical Buenos Aires city inhabitant. This could imply that people spend over two hours a day outdoors. However, this time spent outdoors is on average spent commuting between buildings.

Therefore, upon studying rush hour patters, one may easily identify that the trend is set at two different periods. The first one is in the morning from 8:00 to 10:00 and then there is a second one in the afternoon from 17:00 to 19:00. Under no surprise, this strongly correlates with office hours. Additionally, office hours frequently break at some point at midday between 12:00 and 14:00, for one hour. This typical lunch hour could be exploited by outdoor environments being that people enjoy as a general rule of thumb, a change of setting from an enclosed situation (in a typical office) to an open one (public open space).

Identifying these time patterns (Figure 2.9), one may better understand when most of the pedestrian flow will happen. This is crucial, because it is easier to encourage a person to stay outdoors rather than to lure the same person into an outdoor setting. Therefore, these hours have been used as drivers for this dissertation.

2.5 Transit and staying activities

Figure 2.9: Identification of the three time frames

Table 2.1: Climatic data for Buenos Aires (-34°36’ S, 58°22’ W), Argentina Source: Meteotest 2006

Mean daily air temperature (°C)

As stated before, most of the time people find themselves outdoors is when they are moving from one place to the other. It is acknowledged that pedestrian flow always stimulates city life. Nevertheless, passers-by do not contribute as much to the vitality of a city as people who actually stay outdoors do. A study reveals that on average, people who engage on some sort of activity stay outdoors 9 times as much time as commuters do (Gehl, 2010). Figure 2.10 shows this relationship. This explains why the focus of the dissertation will be placed on staying activities. However, it is also acknowledged that for people to actually stay in a place, it has to be appealing or interesting. For a place to be interesting there has to be pedestrian flow.

Minimum daily air temperature (°C) Maximum daily air temperature (°C) daily wet bulb temperature (°C) Absolute humidity (g/kg) Relative humidity (%) Global horizontal solar radiation (kWhr/m²) Direct horizontal solar radiation (kWhr/m²) Wind speed (m/s) Wind Direction Rainfall (mm.)

8

Transit Activities %

Direct solar radiation Diffused solar radiation

100

80

Mean daily total kWhr/m²

Staying Activities

6

4

2 60

40

30

Mean maximum air temperature Mean daily air temperature Outdoor Activties

Figure 2.10: Relationship transit and staying activities Source: Gehl (2010)

16

Total time outdoors

Mean minimum air temperature

°C

25 20

20 15 10

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2.6 Climate analysis The weather data for the city of Buenos Aires (34°36′S; 58°22′W) here presented was obtained using the meteonorm global meteorological database (Meteotest, 2006). It has been analysed taking into account outdoor comfort rather than indoors. The data is a typical meteorological year averaged from the records collected for the period between 1995 and 2005 in Buenos Aires. A summary of the monthly data is provided in Table 2.1. As can be seen, the different mean daily air temperatures allow for an effective break down of the annual cycle into a warm, a mild and a cool period.

The warm period that runs from December to March inclusive, has the mean air temperatures in the range of 20 to 25°C. There is a five month long cool period with mean daily air temperatures in the range of 10 to 15°C during the months of May to September inclusive. Finally, the interlude remaining may be grouped into a three month long mild period which acts as transition between the former two with mean daily air temperatures between 15 and 20°C.

Warm

Mild

Cool

Mild

Warm

Jan

Feb

Mar

Apr

May

Jun

Jul

Aug

Sep

Oct

Nov

Dec

Yr

24.4

23

22

17.6

14.8

12

11

13

13.9

17.7

19.8

22.5

17.6

21

19.7

19

14.6

12

9.5

8.1

9.9

10.7

14.5

15.2

28.5

14.5

27.9

26.5

25.3

21

18.1

15.1

14.4

16.7

17.4

21.1

23.4

26.3

21.1

19.8

19.1

18.4

14.8

12.4

10

8.8

10.4

10.8

14.3

16

27.7

14.4

13

12

12

10

8

7

6

7

7

9

10

11

9.3

67

70

72

76

78

80

77

75

70

71

70

64

72.5

7.1

6.5

5.2

3.8

2.8

2.2

2.3

3.2

4.3

5.3

6.8

6

4.6

4.3

4.1

3.2

2.3

1.7

1

1.2

2

2.4

2.9

4.4

3.7

2.8

3.5

3.5

3.3

2.9

2.7

2.6

2.8

3.1

3.5

3.9

3.9

3.8

3.3

E

E

N, E

E

N, E

N, W

E, W

N

N, E, S

E

N, E

E

130

126

147

78

21

19

14

28

31

81

145

186

83.3

Figure 2.11: Global solar radiation broken into direct and diffused

Figure 2.12: Mean daily mean, mean daily maximum and minimum dry bulb air temperatures

17

Chapter 2: Context

Additionally, the sun path diagram in Figure 2.13 shows sun angles for the winter and summer solstices along with the spring equinox for 12:00 o’clock corresponding to the latitude of Buenos Aires.

Rodolfo Pedro Augspach

m/s 30 26-30 21-26 17-21

December 21st

September 21st

13-17 9-13

June 21st

4-9 0-4

Figure 2.13: Sun trajectories for the Winter and summer solstice and Spring Equinox

Hours of Occurence

This climate presents predominantly intermediate sky conditions.

Another characteristic is a cumulative temperature deficit below 18°C of 870 heating degree days. Furthermore, it can be appreciated in the frequency graph presented in Figure 2.14 that approximately 50% of the time the temperature is below 18°C. This set point is taken as it is the lower limit of the comfort band for the coolest month (July), calculated according to the model used (see page 26). This hints that the climate is predominantly cool.

28°C 18°C

Air Temperature (C°) Figure 2.14: Temperature frequency along the year

Year round, the mean wind speeds are slightly above 3 m/s and the predominant directions are north and east, consolidating over 50% of the time amongst the two. A wind rose for each of the different periods has been plotted in Figures 3.8 overlaid the Buenos Aires City plan. These show that during the identified warm and mild periods, wind directions are predominantly from the Rio de la Plata. In the cool period however, no strong pattern is identified.

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Warm period

Mild period

Architectural Association School of Architecture

Cool period

Figure 2.15: Wind rose overlaid the Buenos Aires City plan for the identified warm, mild and cool periods respectively.

Warm period

Mild period

Cool period

Conclusions

During the warm period sunlight is available for 14 hours a day and is considerably strong. However, two thirds of the global radiation corresponds to the direct component. Absolute humidity levels are high sometimes reaching levels above the maximum recommended for comfort, of 12g/kg (Szokolay, 2002), indicating air movement could be well received.

Nevertheless, air speeds are available as they tend to be higher than the annual mean at an average of 3.5 m/s over the period. The predominant wind directions are north and east which occur 24% and 28% of the time respectively. Precipitation levels are high with an average monthly rain fall of roughly 150 mm. These happen as heavy rain through short periods of time.

In the mild period, similarly to the previous one, north and east wind directions are predominant. Moreover, for the month of April, air speeds are on the range of 3 m/s, but for the other two months, this speed is 4 m/s. Other discrepancies may be seen in the month of November.

For one, this month shows the highest mean direct solar radiation of the whole year being significantly higher than the registered for the other two months of the period. Additionally it presents a precipitation level similar to that found in the months of the warm period, while the other two have a mean monthly in the range of 80 mm. Nevertheless, what allows for an effective grouping is the air temperature correlation of these months.

The months that make up the cool period are the ones that show the lowest levels of absolute humidity, but the relative remains moderately high. Correspondingly, they also show the lowest levels of precipitation.

Diffused solar radiation is relatively high in comparison to its incidence in other periods, as the direct component makes up for half the global.

There is no clear wind pattern in these months, but it can be seen that south and west wind directions start to occur with increasing frequency.

However, air speeds in these months tend to be the lowest for the year, with a mean of 3 m/s for the period.

Concluding, the climate here presented could be regarded as a mild one, as it presents no extremes. This already hints great potential for outdoor spaces. During the warm period, shading could be very effective in blocking unwanted solar gains, and high air speeds may be used to alleviate the ill-effects of relatively high humidity. As a consequence of these levels of humidity during the warm period, evaporative cooling strategies where not undertaken. The cool period, which is the largest does not present significantly low temperatures, as the daily mean for the period ranges from 8.1째C to 18.1째C. Therefore, the design of outdoor spaces for this period inclusively should be considered.

19

Chapter 2: Context

Rodolfo Pedro Augspach

2.7 Time frame analyses As explained in the former section, the three identified time periods have served as drivers for this study, and therefore, have been studied independently. The different time periods also correlate to each of the identified seasonal periods identified previously. This breakdown is explained in Figure 2.16. The data presented in Table 2.2 shows the average values calculated using the hourly weather file obtained from meteonorm (Meteotest, 2006). The studies are analysed through comparisons of the same time periods in different seasons in order to better understand through differences the details of each.

Table 2.2: Time frame analysis source: After Meteotest 2006

Climatic Period Mean air temperature Mild Period

Cool Period

Monthly minimum air temperature Monthly maximum air temperature Mean wet bulb temperature Absolute humidity Global horizontal solar radiation (kWhr/m)

Wind direction

Direct horizontal solar radiation (kWhr/m)

Afternoon

Midday

(12:00 - 14:00)

Relative humidity

(17:00 - 19:00)

Time Frame

Morning

(8:00 - 10:00)

Warm Period

Figure 2.16: Time frame breakdown

Air Speed > 5.0 m/s 2.5 - 5.0 m/s

In Figure 2.17, wind speeds are plotted as percentages of occurrence. It has been recognized that they tend to decrease during the cool period. This is so for all time frames within this season. In addition, a pattern may be seen in wind acceleration toward the later part of the day resulting in higher wind speeds in the afternoon time frames. Lastly, the wind speed patterns for the warm and the mild periods present very similar characteristics.

When looking at cloud cover patterns in Figure 2.18, it can be easily identified that the cool period presents the cloudiest skies. However, prospects are very good for the midday time frame on the mild and cool period, as the trend indicates that it is the moment of the day with the lowest cloud cover. Nevertheless, during the warm period the pattern is inversed

Figure 2.19 illustrates the frequency of the direct component of the horizontal solar radiation intensity for the different periods. It is recognized that the solar radiation in the morning or the afternoon for the cool period will not contribute much for thermal comfort as it is very seldom above 50 Watts/m². However, at midday it is not too uncommon for the direct component to be well above 100 Watts/ m² for the same seasonal period. Additionally the intensity of the sun during the morning and even the midday time frames seems to be quite similar for the warm and the mild periods. Nevertheless, there is a noticeable difference between these two in the afternoon. This correlates with the predominant clear skies during this time frame for the warm period, and proves that shading at this time should be very efficient for reducing solar gains.

20

0.5 - 2.5 m/s

Cloud Cover 6 - 8 Octas 3 - 5 Octas 0 - 2 Octas

Direct Horizontal Solar Radiation Warm period Mild period Cool period

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Midday (12:00 - 14:00)

Morning (8:00 - 10:00)

Afternoon (17:00 - 19:00)

Warm

Mild

Cool

Warm

Mild

Cool

Warm

Mild

Cool

21.2

16.6

10.6

25

20.6

14.8

26

21.1

15.4

14.2

9.4

3.1

16.3

12.9

5.9

18.1

14.5

5.9

28.2

24.2

18.2

31.3

29.1

23

32.7

30.4

24.2

18.3

14.5

9.4

19.2

15.8

11.3

19.6

16

11.6

12

10

7

12

9

7

12

10

7

76

81

87

58

62

67

56

60

65

255

225

20

755

665

430

420

280

130

150

130

45

450

400

250

260

170

60

N, E

N

N, E, S

E

N, E

N, E, S

E

E

N, E, S

100

100

100

50

50

50

0

0

0

Figure 2.17: Frequency of different air velocities for the different time frames in the different periods 100

100

100

50

50

50

0

0

0

Figure 2.18: Frequency of different sky cover conditions for the different time frames in the different periods %

%

%

100

100

100

80

80

80

50

50

50

20

20

20

0

100

200 W/m²

300

0

100

250

500 W/m²

700

0

100

200

300

400

W/m²

Figure 2.19: Frequency of intensity of the direct component of the solar radiation for the different time frames in the different periods

21

3.

Analytic Work

3.1 Outdoor comfort 3.2 Pedestrian thermal comfort in the Spanish grid

Chapter 3: Analytic Work

Rodolfo Pedro Augspach

4.1 Outdoor Thermal Comfort

Introduction

Parametric studies have been conducted in order to better understand the individual and combined thermal effects of wind and solar radiation upon a person within the Buenos Aires climatic context. The sole goal of this particular study is to determine how thermal comfort can be achieved outdoors.

In this assessment of thermal comfort, Physiological Equivalent Temperature (PET) simulations were carried out using the Rayman © research tool. The external parameters required for the simulations are:

Parameters considered

- Julian Date - Time - Air temperature - Relative humidity - Wind velocity - Cloud cover - Global radiation

For each of the nine scenarios, the data for the parameters was extracted from the hourly weather file respectively, presented in the previous section. However, values for wind and solar radiation were assigned in order to carry out the sensitivity studies. Figure 3.1 shows the solar radiation runs for each of the wind speeds, for all time frames of the three periods. Simulations with air speeds higher than 5 m/s were not carried out because it is recognised that the mechanical effects beyond these speeds are more significant than the thermal effects (Nikolopoulou, 2002).

These simulations were possible because in the PET simulations Rayman© calculates the effect of the different ratios of cloud cover upon solar radiation. However, it needs to be stated that this sensitivity study is coupled with the previous period analysis. This means that the available global horizontal solar radiation for the different periods limits the runs when they would seem pointless.

Climatic period (days)

Time frame (hours)

Air speed (m/s)

Solar radiation (W/m²) 50 100

0.5

Warm period Mild period Cool period

Morning (8:00 - 10:00)

Mid day (12:00 - 14:00)

Afternoon (17:00 - 19:00)

200 1 300 2 400 3 500 4 600 5 700 800

Figure 3.1: Parameter values for the different iterations ran

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Moreover, because the focus of the study is the thermal effects upon a user, a hypothetical case was created. This hypothetical individual has the following personal characteristics:

- Gender : Male

- Weight : 75 kg - Height : 1.75 - Age : 35

Clo

This theoretical person was then drawn for each of the three climatic periods and clo values were adjusted according to season. This clothing presented in Figure 3.2 is based on cultural trends of how much clothing Argentinians commonly wear. The Clo values calculated are based on ASHRAE (1985). Additionally a correction factor must be applied of 0.82 when adding clo values (Auliciems & Szokolay, 1997).

Metabolic rate

In addition, the metabolic rate for all simulations has been fixed to 100 Watts. This corresponds to sedentary activities. These will be the conditions studied for the reasons discussed previously.

The need for the correlation between PET and PMV

Although PET calculations were used to simulate a personâ&#x20AC;&#x2122;s thermal sensation a correlation had to be established with the PMV thermal index. This correlation was found necessary because PET calculations are made with fixed clothing and metabolic rate values of 0.9 Clo and 80 Watts respectively, whilst the PMV index is sensible to both parameters.

PET and adaptive comfort

Warm Period

Preceding the correlation between PET and PMV, it is necessary to link both models individually to comfort. This will allow for a better understanding of the two methodologies along with a more effective linking between the two. The connection between the two models has already been established and associated with thermal sensitivity by previous authors (Matzarakis & Mayer, 1996). However, in this study they will also be linked to a model of adaptive thermal comfort. The purpose of this is to account for the adaptation of people to the varying climate along the year.

Mild Period

jacket, light 0.12 Clo.

long sleeve shirt 0.14 Clo.

Cool Period

jacket, light 0.22 Clo.

jacket, medium 0.39 Clo.

pullover, light 7 Clo.

pullover, heavy 0.37 Clo. long sleeve shirt 0.29 Clo.

trouser, heavy 0.32 Clo.

trouser, light 0.26 Clo.

trouser, heavy 0.32 Clo.

trouser, heavy 0.32 Clo.

socks & shoes 0.13 Clo.

socks & shoes 0.13 Clo.

socks & boots 0.12 Clo.

Adjusted clo

0.5 Clo.

Adjusted clo

0.9 Clo.

Adjusted clo

1.2 Clo.

Figure 3.2: Clothing values used for simulations for the different seasonal periods.

25

Chapter 3: Analytic Work

Addaptive thermal comfort model

Rodolfo Pedro Augspach

Furthermore, the fact that PET is the thermal equivalent to indoor air temperatures allows for the model of indoor adaptive comfort proposed

by De Dear to be applied. The equation proposed by De Dear and used in this study is here presented:

Tn = 17.8 + 0.31Tm

(eq. 1)

tn = Comfort temperature Tm = Monthly mean temperature

Additionally, in order to plot the comfort bands corresponding to 90% acceptability, 2.5째K had to be added and subtracted. The applied equation with the comfort band is plotted in Figure 3.3.

Cool period

Mild period

Warm period

30

Comfort temperature

27.5 25 22.5 20 17.5

10

15 20 Outdoor air temperature

25

Figure 3.3: Adaptive thermal comfort equation and band for 90% acceptability with the three climatic periods marked

Percentage of people dissatisfied

PMV and comfort

Alternatively, the PMV thermal index may be linked to comfort through the percentage of people displeased formula presented by Fanger (1970) and shown here in Figure 3.4.

80 60

80 60

40

40

20

20

10

10

5

5 -2.0

-1.5

-1.0

-0.5

0

0.5

1.0

1.5

2.0

Figure 3.4: Connection between PMV and PPD Source: Fanger (1970)

Nonetheless, when associating all models with comfort, discrepancies appear as one can see in Figure 3.5. These discrepancies are expected up to a degree because the adaptive model selected was originally intended for indoors.

Upon studying the connections made, it may be detected that the adaptive model appears as the most sensible, having the thinnest comfort or neutral band, and therefore, presenting the most problems. This is because the model used supposes a limited array of adaptive opportunities, commonly found in indoor situations such as an office building. However, in a successful outdoor scenario, the opportunities are plenty, suggesting that bands widen considerably.

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MArch Sustainable Environmental Design 2011 - 2013

PET

-3.5

4

-2.5

8

-1.5

13

-0.5

18

0.5

23

1.5

29

2.5

35

3.5

41

Calculated adaptive PET

Grade of thermal stress

Warm period

Mild period

Cool period

8

6

4

12

10

8

17

15

13

22

20

18

27

25

23

31

29

27

37

36

34

43

42

40

Extreme cold Strong cold Moderate cold Slight cold Neutral Slight heat Moderate heat Strong heat Extreme heat

Figure 3.5: Relationship between PMV, PET and adaptive thermal comfort Source: After Matzerakis & Mayer (1996)

Therefore, what needs to be considered is that the closer temperatures are to the neutral band, the more comfortable users will tend to find the space. It does not necessarily state however, that temperatures outside this range will be found uncomfortable in an outdoor setting.

The correlation between PET and PMV

Finally, having already linked the models to adaptive comfort, it was still necessary to establish a relationship amongst them. This was possible through the simulation of one time frame and weighing the results of PMV and PET for all the hours within that frame. The period where the time frame had to be chosen from was the mild one. This had to be so because the user has 0.9 clo, in this period which coincides with the fixed value for PET. Therefore, both models calculated with the same inputs.

Which time frame is chosen doesnâ&#x20AC;&#x2122;t make a difference. For this comparison however, the morning period was chosen, and all solar iterations for 0.5 m/s were plotted. The results of this connection are plotted in Figure 3.6 showing a clear linear relationship. This relationship is translated into equation 2.

-3

PET

PMV

Architectural Association School of Architecture

-2

PET = 5.927 x (PMV) + 21.285 -1

0

1

2

(eq. 2) 3

40

40

30

30

20

20

10

10

0

-3

-2

-1

0

1

2

3

0

PMV Figure 3.6: Relation between PET and PMV simulation results for all iterations with 0.5 m/s for the hours within the morning time frame of the mild period.

27

Chapter 3: Analytic Work

Methodology for formula development

Rodolfo Pedro Augspach

This equation proves to be quite accurate for PMV values close to 0, but it presents problems with more extreme situations. However, this is not a problem, because PMV was already found not to be reliable with temperatures below 10 or above 30 (Nicol & Humphreys, 2002).

Once a formula for converting PMV was achieved it became possible to calculate the incidence of different clo and metabolic rate values upon PET. Figure 3.7 shows the methodology followed and the selected inputs for this calculation, in a step by step format.

Methodology

Selected inputs

Any climatic period in which subjects have clo values ≠ 0.9 clo is selected. (days)

Warm period (0.5 clo)

Select any time frame (hours within those days)

Morning time frame

PMV and PET are simulated

PMV is converted into PET ’ through the use of Eq 2

The differences between PET and PET ’ are computed (Δ PET)

The differences between clo values are computed (Δ clo)

0.9 clo - 0.5 clo = 0.4 clo (Δ clo)

The incidence of 0.1 clo (Δ PET ’) is established by computing Δ PET/ Δ clo

Δ PET / 0.4 = Δ PET ’ PET incidence of 0.1 clo

The differences are then related to the corresponding PET value Figure 3.7: Methodology followed for calculating the formulas for the incidence of clo and metabolic rate upon PET.

Clothing

Figure 3.8 shows the established relationship between the different PET values and their corresponding influence of a 0.1 clo change. This shows again a linear trend which may be translated into equation 3 as follows:

Δ PET ‘ = -0.0856 x PET + 2.9

PET = Simulated results with fixed 0.9 clo Δ PET ‘ = Incidence of 0.1 clo change in PET sensation 28

(eq. 3)

MArch Sustainable Environmental Design 2011 - 2013

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2.5 2.0

PET incidence (K°)

1.5 1.0 0.5 0

10

20 PET (C°)

30

40

Figure 3.8: Graph showing effects of removing 0.1 clo for different PET results.

Metabolic Rate

Additionally, the same methodology and steps were carried out to develop a similar tool for assessing metabolic rate changes. The common denominator in this case was set at a 20 Watt increase. Again the results were related, as shown in Figure 3.9 and the equation here transcribed (eq.4).

Δ PET ‘ = -0.092 x PET + 3.6

(eq. 4)

PET = Simulated results with fixed metabolic rate of 80 Watts Δ PET ‘ = Incidence of 20 Watt change in PET sensation 2.5 2.0

PET incidence (K°)

1.5 1.0 0.5 0

20 30 40 PET (C°) Figure 3.9: Graph showing effects of increasing metabolic rate by 20 Watts for different PET results.

10

Conclusions

Both equations tend to be quite similar. Figure 3.8 shows that adding or removing clothing has a higher effect on thermal sensitivity within lower temperatures. Similarly, a metabolic rate increase has a higher effect within lower thermal sensations. Finally, it has to be noted that again when temperatures become too extreme, the formulas start showing errors. Nevertheless, it does not present a problem for this investigation, as the comfort temperatures which are under focus are not close to these extremes.

29

Chapter 3: Analytic Work

Application of the formulas

Table 3.1: Lower and upper limits of the adaptive thermal comfort band for the different periods.

Warm

Mild

Cool

Lower limit

22

20

18

Upper limit

27

25

23

Subsequent to simulating PET, the results needed to be converted in order to account for the corresponding clothing values for the different periods. In addition, as all PET simulations were ran considering 80 Watts, an increment was required to contemplate the 100 Watts corresponding to the metabolic rate of a seated person. These differences were calculated through the use of equations 3 and 4 as explained in Figure 3.10. This diagram shows that the first equation applied was the clo conversion.

Moreover, the simulation results for the mild period did not require this as the calculated PET considers the same clothing level as the one assigned for that period. The second conversion was made to adjust the metabolic rate through equation 4. These converted PET results will be called from now on PET “.

Furthermore, all PET “ results were analysed against the adaptive thermal comfort band presented previously. The lower and upper limits of the comfort band for each season are again shown in Table 3.1.

Moreover, the percentage of hours when the PET “ is within this range for the different iterations is plotted in the graphs of Figure 3.11. One enters these graphs with one combination of horizontal solar radiation and air movement for a particular time frame. The lighter the colour is for this combination, the higher the percentage of hours to be found in the range of the comfort band within the specific time frame. However, it does not mean other combinations are uncomfortable. Other combinations will probably be comfortable for less number of days, or demand more adaptive opportunities from the individual, such as adding or removing clothing.

Warm Period

Morning

8:00 - 10:00

Midday

12:00 - 14:00

Mild Period Afternoon

17:00 - 19:00

Rodolfo Pedro Augspach

Morning

8:00 - 10:00

Midday

12:00 - 14:00

Cool Period Afternoon

Morning

17:00 - 19:00

8:00 - 10:00

Midday

12:00 - 14:00

Afternoon

17:00 - 19:00

PET wind and solar iterations (explained in Figure 4.1) Equation 3 is applied to all the results in order to convert them into PET with Clo value of 0.5

Equation 3 is applied to all the results in order to convert them into PET with Clo value of 1.2

PET ‘ = PET - [(-0.0856 x PET+ 2.9) x 4]

PET ‘ = PET + [(-0.0856 x PET+ 2.9) x 3]

Equation 4 is applied to all the results in order to convert them into PET with metabolic rate of 100 Watts PET ” = (-0.092 x PET ‘ + 3.6) + PET ‘ Figure 3.10: Diagram showing simulation steps and methodology for calculating the comfort graphs

The comfort graphs

In these graphs the minimum solar radiation a space requires to provide comfortable conditions for the most possible time has been noted.

Under the same criteria, the maximum has been also marked. However, this is only so, when applicable. In addition, the more slanted the lines are, the stronger the thermal effect of the wind for the given time frame.

Therefore, it can be readily identified that the sensitivity to these effects is greater during the mild period.

Additionally, the cool period shows the highest percentage of hours within comfort for the iterations, but it does not mean that it is easier to achieve comfort in this period than in others. However, this only shows that the other parameters in this climatic period vary less. Therefore, what is needed for one of these hours to be comfortable in terms of sun and wind is usually what is required for the rest of the hours. Hence, the remaining climatic periods have a preference of requirements shown in the lighter colours, but for the other hours no combination is conclusive.

30

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Warm period

Architectural Association School of Architecture

Mild period

Cool period 60-70%

50-60%

40-50%

30-40%

50-60%

40-50%

30-40%

50-60%

40-50%

30-40%

20-30%

10-20%

0-10 %

20-30%

10-20%

0-10 %

20-30%

10-20%

0-10 %

Morning (8:00 - 10:00) W/m² 500

W/m² 500

400

400

300

300

200

200

100

100

W/m²

200 100

1

2

3 m/s

4

5

1

2

3 m/s

4

5

1

2

3 m/s

4

5

50

Midday (12:00 - 14:00)

1

2

3 m/s

4

W/m² 800

W/m² 800

700

700

600

600

500

500

500

400

400

400

300

300

300

200

200

200

5

100

1

2

3 m/s

4

100 5

W/m²

1

2

3 m/s

4

100 5

Afternoon (17:00 - 19:00)

1

2

3 m/s

4

W/m²

W/m²

500

500

400

400

300

300

200

200

100

100

5

1

2

3 m/s

4

5

W/m²

200 100 1

2

3 m/s

4

5

50

Figure 3.11: Comfort graphs for the different periods of the different seasons.

31

Chapter 3: Analytic Work

Investigation of adaptive strategies

Rodolfo Pedro Augspach

Following the simulations, it was possible to estimate the mean PET variation which corresponds to a modification in solar or wind exposure.

To calculate this, the results for each of the iterations were averaged.

Figure 3.12 shows the process done for all nine time frames. Additionally, the same figure shows an example for the morning time frame of the mild period. This same process was repeated for all the simulations. In all situations, the °K is always in comparison to a starting point which is the least exposed to solar radiation and air movement.

The outcome of this particular study for each time frame is shown in Figure 3.13. It can be seen in this figure that for the cool period adaptive opportunities are very much reduced. Additionally, one can assess the thermal impacts of moving from one area with one set of conditions to another one for all time frames.

To summarize, table 3.2 shows the adaptive opportunities studied in this section. The effects of personal adaptation, such as clothing and metabolic rate changes, have been calculated using equations 3 and 4.

However, instead of applying PET values to the equations, the mean air temperatures for the different time frames were used, taken from the previous chapter. This was so in order to calculate the effects of the adaptations independent of sun and wind. From this table one may detect that during the cool period, the personal adaptive strategies, have an almost equal incidence thermally as exposing oneself to the sun. Nevertheless, this is not so for the midday time frame of the same period.

Table 3.2: Impact of adaptive opportunities upon thermal comfort for the different time frames. (°K)

Climatic period (days)

Mild Period

Time frame (hours within those days)

Morning 8:00 - 10:00

Wind speed iteration

0.5 m/s

Solar radiation iteration

100 W

200 W

Average of all simulation results for these hours

15.3 ° PET

18.0 ° PET

Computed differences with starting point averages

18 - 15.3 = 2.7

Weight averages to determine the mean effect of solar radiation and wind speed increments

2.7 ° K

Figure 3.12: Sequence for discerning the K difference with different degrees of solar and wind exposure

Morning

32

Midday

Afternoon

Warm

Mild

Cool

Warm

Mild

Cool

Warm

Mild

Cool

Add or remove clothing (0.1 clo)*

1.1

1.5

2.0

0.8

1.1

1.6

0.7

1.1

1.6

Increase Metabolic rate (+20 Watts)*

1.7

2.1

2.6

1.3

1.7

2.2

1.2

1.7

2.2

Move from shaded and protected to sunny and protected

17

13

3

23

19

9

19

13

3

Move from Shaded and protected to shaded and exposed

-4

-4

-4

-4

-6

-4

-4

-4

-4

MArch Sustainable Environmental Design 2011 - 2013

Warm period

Architectural Association School of Architecture

Mild period

22 - 24 °K

20 - 22 °K

18 - 20 °K

16 - 18 °K

14 - 16 °K

4 - 6 °K

2 - 4 °K

0 - 2 °K

-2 - 0 °K

-4 - -2 °K

Cool period 12 - 14 °K

10 - 12 °K

6 - 8 °K

8 - 10 °K

Morning (8:00 - 10:00) W/m² 500

W/m² 500

400

400

300

300

200

200

100

100

W/m²

200 100

1

2

3 m/s

4

5

1

2

3 m/s

4

5

1

2

3 m/s

4

5

50

Midday (12:00 - 14:00)

1

2

3 m/s

4

W/m²

W/m²

800

800

700

700

600

600

500

500

500

400

400

400

300

300

300

200

200

200

5

1

2

3 m/s

4

5

100

W/m²

1

2

3 m/s

4

100 5

Afternoon (17:00 - 19:00) W/m² 500

W/m² 500

400

400

300

300

200

200

W/m²

200 100

1

2

3 m/s

4

5

100

1

2

3 m/s

4

5

100

1

2

3 m/s

4

5

50

Figure 3.13: Comfort graphs for the different periods of the different seasons.

33

Chapter 3: Analytic Work

Rodolfo Pedro Augspach

4.2 Pedestrian thermal comfort in the Spanish grid As stated previously, the Spanish grid dominates the consolidated urban tissue of Buenos Aires. Pedestrian thermal comfort within it had to be assessed so as to understand the extent of the adaptive opportunities offered by the surroundings of the site. Its rigid nature allows for certain parameters to be extracted in order to be analysed individually. The four models studied were:

- - - -

Minimum Intensity of Direct Horizontal Solar Radiation 20% of the time Minimum Intensity of Direct Horizontal Solar Radiation 50% of the time Intensity of Difused Horizontal Solar Radiation

Medium Density I North - South Axis Medium Density I Northeast – Southwest Axis High Density I North – South Axis High Density I Northeast – Southwest Axis

Maximum established in Figure 4.11 Minimum established in Figure 4.11

High and medium density, are defined in this case by the limitations set by the Buenos Aires building code. These regulations may be translated into the following height to width canyon ratios:

- -

Medium density 1:1.2 High density 1: 1.75

The simulations have been run in order to assess the solar availability within the Spanish grid and compare results for the pavements of the following canyons and corners.

- - - - - -

North – South East – West Corner 1 (N – S axis) North west – South east North east – South west Corner 2 (NW – SE axis)

Furthermore, the first model used for this investigation is here presented in Figure 3.14. The model presents the typical street width for the city of Buenos Aires of 17.6 metres. The height is of 21.2 metres, corresponding to the medium density height to width ratio. The whole block is the same height. This is seldom happens in the real scenario, but it was simulated so in order to focus only on the effect of orientation.

Figure 3.14: Medium density model used in the simulations.

Ecotect Analysis 2011 was used to calculate the direct and diffused horizontal solar radiation falling on the canyons presented. However, it has been identified that for the simulation, the software averages the results over a range of time and space. This translates into averages for the periods set. In this case, all 9 time frames have been simulated so results are the average for the corresponding 2 hours. However, it also means that it averages spaces that receive sun with spaces next to them which do not. This does not present a problem for the diffused component. Nevertheless, it does present a problem for the direct component, undermining its effect.

34

Methodology

MArch Sustainable Environmental Design 2011 - 2013

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Moreover, the starting point for this investigation was the calculation of the diffused horizontal solar radiation for each time frame, independent of orientation. This was possible because this parameter is linked to the sky view factor which does not vary from canyon to canyon. These values are displayed in Figure 3.15.

1200

1000

800

600

400

200

Canyon

Corner

Morning

Canyon

Corner

Midday

Canyon

Corner

Afternoon

Warm Period

Canyon

Corner

Canyon

Morning

Corner

Midday

Canyon

Corner

Afternoon

Canyon

Corner

Morning

Mild Period

Canyon

Corner

Midday

Canyon

Corner

Afternoon

Cool Period

Figure 3.15: Canyon and corner Global horizontal solar radiation intensity according to the different time frames of the different periods.

Assessment of the direct component

Built upon these, the intensity of the direct component for the given period is plotted. This intensity corresponds to the minimum values found 50 and 20% of the time taken from the previous period analysis found in Figure 2.19. These values are here shown in table 3.3.

Table 3.3: Direct horizontal solar radiation levels in relation to frequency of occurrence for the different periods 50 % Warm period

Mild period

Cool period

20 %

Morning

100

50

Midday

590

800

Afternoon

250

400

Morning

60

375

Midday

300

800

Afternoon

100

380

Morning

25

100

Midday

250

550

Afternoon

25

50

This was done so to better understand how much global solar radiation one would receive in a canyon if protected or exposed to the sun.

Additionally, the solar radiation requirements, brought from the comfort graphs (Figure 3.11) were marked on this graph. This enables one to determine when solar radiation is desired and when it is not.

Finally, what needed to be weighed was how much direct horizontal solar radiation exposure each canyon had. Therefore, percentage of hours of direct sun was calculated for each canyon within the different time frames, as shown in Figure 3.16 in the following pages. The images in this figure allow one to determine which possibilities each canyon offers at the different time frames.

35

Chapter 3: Analytic Work

Rodolfo Pedro Augspach

North South Axis Warm period

Cool period

%

%

%

100

100

100

50

50

50

20

20

20

%

%

%

100

100

100

50

50

50

20

20

20

% 100

50 20

36

Mild period

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North West - South East Axis Warm period

Mild period

Cool period

%

%

%

100

100

100

50

50

50

20

20

20

%

%

%

100

100

100

50

50

50

20

20

20

%

North - South Canyon 80

East - West Canyon

70

Corner 1 N-S Axis

60

Northwest - Southeast Canyon

50

Northeast - Southwest Canyon

40

Corner 2 - Northwest - Southeast axis

30

The most sun - When not desired

20

The most sun - When desired

Figure 3.16: Percentage of hours exposed to direct horizontal solar radiation for the different periods in the canyons and corners of a North - south grid and a Northwest - Southeast grid. From top to bottom: Morning, midday and afternoon time frames. The afternoon time frames not displayed simply show no hours of sun in the canyons.

37

Chapter 3: Analytic Work

Rodolfo Pedro Augspach

The images which have been marked are the ones that present the canyons with the most sun throughout the specific period. However, during midday and the afternoon of the warm period solar radiation is not desired. Hence, the canyons which receive the most through this period are marked with the red dotted line. Taking a closer look, one can see that the canyons which receive the most desired sunshine at the studied intervals of time are the ones which belong to the North â&#x20AC;&#x201C; South axis.

Nevertheless, it is important to note the amount of hours of sunshine that the tilted axis allows for during the morning of the cool period.

Percentage of total Hours with direct solar radiation (%)

When breaking down the canyons individually as shown in Figure 3.17, their individual solar availability for the different periods may be assessed. From this graph, Table 3.4 has been drawn categorizing the canyons based on their performance for the different time frames.

100 80 60 40 20

Morning

Midday

Afternoon

Warm Period

Morning

Midday

Mild Period

Morning

Midday

Cool Period

Figure 3.17: Percentage of hours with direct solar radiation in the different canyons for the different periods.

North - South Canyon

Percentage of total Hours of direct solar radiation lost with density increase(%)

This table shows that there is not one canyon that offers the best possibilities for all time frames, but rather a range of different canyon orientations are preferred. In addition, when density is increased the percentage of hours of sunlight per canyon, naturally drops. This drop, as can be seen in Figure 3.18 is more pronounced for the mild and cool periods, when the sun angles are lower.

Northwest - Southeast Canyon Northeast - Southwest Canyon

20

15

10

5

Morning

Midday

Warm Period

Afternoon

Morning

Midday

Mild Period

Figure 3.18: Percentage of total Hours of direct solar radiation lost with density increase

38

East - West Canyon

Morning

Midday

Cool Period

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Table 3.4: Canyon preference for the different time frames.

Best Warm Period

E-W

Ne - Sw

Nw - Se

N-S

Midday

E-W

Ne - Sw

N-S

Nw - Se

-

-

-

E-W

Morning

E-W

Ne - Sw

Nw - Se

N-S

Midday

Nw - Se

N-S

E-W

Ne - Sw

Morning

Ne - Sw

E-W

-

-

Midday

N-S

Nw - Se

Ne - Sw

E-W

Afternoon Mild Period Cool Period

Worse

Morning

Moreover, the canyons which present the most significant drops for the different orientations were the ones that had the least solar exposure in the first place. This is because they were more reliant on solar profile rather than on the azimuth angle for their solar exposure.

As an example, the sky view factors of a N-S and a Nw-Se canyon are displayed in Figure 3.19. In the image, it becomes clear that the former will have less obstructions with density for the midday of the cool period than the latter.

Figure 3.19: Sky view factors for North - South and Northwest - Southeast canyons of the medium density case

Similar studies were conducted for the diffused component of the solar radiation. Figure 3.20 shows that with the density increase the highest rate of loss of diffused solar radiation is within the canyons rather than in the corners. This is a consequence that the sky view factor is more sensitive to building height increase in the canyons than in the corners.

In the same graph it is possible to detect that the drop is steeper in the cool period.

Corners Canyons Reduction of diffused solar radiation (%)

35 30 25 20 15 10 5

Morning

Midday

Afternoon

Warm Period

Morning

Midday

Mild Period

Afternoon

Morning

Midday

Afternoon

Cool Period

Figure 3.20: Percentage of reduction in diffused solar radiation due to density increase for the different time frames.

39

4.

Predesign studies

4.1 Wind studies 4.2 Solar studies

Chapter 4: Predesign Studies

Rodolfo Pedro Augspach

4.1 Wind studies Always with high air speeds

As the site presents scattered free standing tall buildings it is expected to be windy. In order to understand these wind patterns, computer fluid dynamic studies have been performed on site. Twelve simulations have been ran using Winair 4 © for orientations every 30° for the 2013 setting.

Each run was with 500 iterations and the cell block was 5 x 5 x 5 metres.

For all the runs, the air speed given was 12 m/s. Additionally, the runs were performed on the 2015 scenario, to understand the effect of the 3 additional towers

In the annual wind rose of Figure 4.1 one may identify the three predominant wind directions which are 30°, 60° and 90° clockwise from North. Hence, the simulation results for these are illustrated along with the same wind directions for the 2015 scenario in Figure 4.2. This allows for an effective comparison between one scenario and the other. Additionally, an overlapping of the three for each of the two scenarios has been carried out as a conclusion. This enables one to detect patterns of high and low turbulence.

Conclusions

2013

Upon a closer look at the 2013 scenario, one can see that there are few areas protected throughout the site. This in itself hinders drastically any potential for sedentary activities. High turbulence in the avenue itself could be welcomed in order to more effectively disperse pollution.

However, these also have a negative effect on the acoustic environment.

(Szokolay, 2008)

Always with low air speeds

However, in the 2015 scenario, with the addition of the three towers, wind patterns changed substantially. For one, when wind is blowing from the East Northeast direction (60°), there is considerable air speed acceleration. However, overall air speeds for the avenue are significantly diminished.

Nonetheless, when studying the protected areas these buildings offer, one can conclude that these are a bare minimum. The additional towers diminish overall air speeds, but offer few overall protected areas.

The only effective protection they grant is to their immediacies.

m/s

26-30 21-26 17-21 13-17 9-13 4-9 0-4

Figure 4.1: Wind rose for the whole year

42

2015

30

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m/s > 5.0

4.0

2.0

5.0

3.0

1.0 0.5

30째

60째

90째

Figure 4.2: CFDs for the 3 predominant wind directions

43

Chapter 4: Predesign Studies

Rodolfo Pedro Augspach

Has sun in all three periods Never has sun in these periods

Conclusions 4.2 Solar studies

In Figure 4.4 percentage of hours of sun for the midday of the cool period is shown along with the same simulations for the morning and afternoon of the mild period. As identified in the “comfort outdoors” section, these are critical periods. This means sun angles are low, but direct exposure tends to make a difference upon thermal comfort.

2013

When assessing solar availability, the focus was placed again on percentage of sunlight hours, as in the case of the Spanish grid analysis.

The calculation of hours of sunshine on site within the different time frames was carried out with Ecotect Analysis 2011, and it enables one to weigh the resources available in the context.

Additionally, a similar methodology of overlapping was carried out to assess which areas were constantly shaded during the critical hours displayed, and which are always exposed. The impact of the three additional towers on this “layer” may also be assessed.

2015

The highest impact on site would be from the circular tower to the north, precisely because of its location, all its shade is cast upon the site limits. This tower has the highest impact on the ground floor for the midday period. In addition, the triangular one to the middle of the site has a strong impact on the morning, and even the afternoon period.

Figure 4.3: Sun path diagram with focused time frames highlighted

44

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% 100

60

30

80

50

20

70

40

0

Cool period Midday

Mild period Afternoon

Mild period Morning

Figure 4.4: Percentage of hours of direct sunlight for the â&#x20AC;&#x153;critical periodsâ&#x20AC;?.

45

5.

Design Proposal

5.1 Design brief 5.2 Establishment of the site 5.3 Structuring the ground floor 5.4 Density 5.5 Assessing the wind environment 5.6 Area of focus

Chapter 5: Design Application

Rodolfo Pedro Augspach

5.1 Design Brief The lessons from the theoretical background explain why the Catalinas Norte development is so unattractive for pedestrians. The problems identified in the context and analytic work chapters prove that the site provides the perfect setting for testing the hypothesis.

This hypothesis will be tested on site according to the diagram on Figure 5.1. In order to integrate the site to the rest of the city the width of the avenue should be reduced. Presently it works like an urban barrier, effectively hindering pedestrian flow.

As an outcome, it becomes possible to expand the pavement over the avenue to meet the rest of the city. This expansion results in a lower plot ratio for the site. Hence, in order to preserve the built density, additional buildings should be projected.

These buildings will play the major role of confining the already existent and the new public space. They should serve as active walls for these spaces, stimulating pedestrian flow. Programmatic variety will be added in order to overcome the zoning limitations the site presents. This zoning filled the scene with office buildings which have fixed day to day schedules as seen previously.

In order to stimulate vitality it is important to incorporate variety.

This may be achieved by projecting spaces that have opposite peak demand hours such as cafes and bars. The number of potential customers on site sustains the demand for these services. Additionally, housing and residential areas were added to the mix, and the plan depth has been limited by the passive zone concept in order to encourage passive design.

Similarly, it has been identified that plot widths should be kept to a minimum. This could evoke a very active ground floor, which will help enliven the open areas around it. In addition, these open areas should be given a clear structure. This implies assigning ownership and responsibility over a given space to different programmes, such as cafes, retail or housing. When assigned to the latter this should be in a hierarchical manner, so as to create a sense of belonging, and therefore, community (see theoretical background).

Finally, for these spaces to be used, pedestrians should be drawn to them. The flow is inevitably there already given the presence and character of the towers. Nevertheless, for these areas to be able to retain individuals, they should provide comfortable conditions. Therefore, comfort criteria needed to be established.

However, it has been recognized that several different microclimates are better received than one optimal condition. Hence, the criteria used to assess if one space can be deemed as comfortable will be directly related to the range of possibilities such a space offers. The limit however, will be to have at least one area within the space that meets the thermal requirements of sun and wind for 50% of the time for at least one time frame. These thermal requirements have been extracted from the comfort graphs (Figure 3.11). Lastly, a strong visual link had to be established amongst these areas, in order to facilitate user adaptation to the spaces.

48

Brief

Integration of the Catalinas Norte devolpment Reduce the width of 60 metre wide avenue decreasing the road area Expand the pavement over the previous road area Build over the new pavement enough as to maintain the Plot ratio of 2015

MArch Sustainable Environmental Design 2011 - 2013

Architectural Association School of Architecture

Bars / Cafes

Add programmatic variety

Retail

Residential

Passive zone concept

h 2h

Divide street frontages into numerous small lots with reduced lot width

Add vitality

Structure and categorize the public domain

Encourage prolonged stay of pedestrian activities

Areas whithin spaces which offer thermally comfortable conditions 50% of the time for at least one time frame throughout the year

Str

Strong visual connections between these areas

on g co visua nn ec l tio n

Figure 5.1: Design brief and strategies to follow

49

Chapter 5: Design Application

Rodolfo Pedro Augspach

5.2 Establishing the site

Floor area ratio

At present day, the site has a built density which is higher than the one found in the medium density parts of the consolidated urban tissue, as seen in Figure 5.2. The density has been calculated in all scenarios as a built floor area ratio. Therefore, the results are given in number of built m² per 1 m² of ground floor. This calculation was done assuming a floor to floor height of 3.5 metres for all models. The fact that a ratio was calculated for all scenarios, allows for an effective comparison.

The five scenarios presented in the graphs are: Spanish grid medium and high density block, site with existing buildings, site with 2015 towers, and site with the 2015 towers and the expansion over the avenue.

The first thing one may identify is that the current buildings have a higher density than the medium density block, but lower than the high density scenario. However, with the introduction of the three new towers, the site will have a floor area ratio more than 30% higher than the Spanish grid high density block.

Floor area ratio (built m²/ground floor m²)

8 7 6 5 4 3 2 1 0 Spanish grid medium density

Spanish grid high density

Figure 5.2: Floor area ratio for panish grid medium and high density, and the different scenarios on site.

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Nevertheless, the site is privileged with such a good transport infrastructure (see chapter 2) in a key location of the city, that high density could be well received. Nonetheless, when the ground area of the buildings is increased, floor area ratio decreases proportionally. Therefore, to maintain the built density of the 2015 scenario, while expanding the pavement, an additional 125000 m² have to be projected. This is one of the guidelines established in the brief.

Additionally, the solar path in Figure 5.3 shows the strategy followed for extending the ground streets and ground floor. The roads were extended or maintained wherever they matched the azimuth angle of the hours of focus where the sun is wanted. This followed the findings of the previous Spanish grid analysis, and will ensure much desired solar availability in the canyons. Additionally, the road added follows the same criteria.

Figure 5.3: Sky view factor with the highlighted period of focus. This shows the angles followed for extending the roads

125.000 m ²

Site in 2013

Site in 2015

Site with expansion of ground floor area

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5.3 Structuring the ground floor Present pedestrian flows

Altering pedestrian flows

As discussed previously, the current scenario presents several problems.

For one, it offers little diversity or attractions for pedestrians. Additionally, traffic makes crossing a risky feat. In order to avoid being caught in the middle of the road when crossing, one must cross from specific points.

Upon traversing, one finds oneself in a situation which offers few protections from the elements (sun or wind) and no possibility of looking at anything other than the towers. On the other consolidated side, people may stop to do window shopping or even get refreshment in a kiosk. In addition, one may walk under the shade of buildings if so desired. As a result, pedestrians only cross the avenue to reach their final destination. As seen in Figure 5.3, the situation with the 3 additional towers in the 2015 scenario does not offer considerable change.

The buildings introduced in the proposal were set to alter these flows. They were set at a close distance from the consolidated tissue and the towers closing the gap between them. Moreover, the curvy shape was chosen to contrast the regular geometry of the two parties. The main purpose of these buildings over all was to structure and hierarchize the ground floor. This process consisted on enclosing particular spaces.

These retain a semi-public character. However, because of the close connection to a limited number of lots, a sense of property and belonging is created. Assigning a space to a reduced number of lots guarantees a better maintenance of it.

In addition, in order to successfully alter the flows, variety needed to be included on site. This plays a key role in drawing people to and across the site. The new activities which will begin to appear will offer a more interesting scenario luring pedestrians and integrating the patch to the rest of the city. In the plan on Figure 5.5 one can see how the mixture of programmes found in the Spanish grid spills over the site with the new proposal.

Moreover, it is important to note that the elements referenced as “grocery stores” (green colour) on site don’t necessarily need to be so. These lots were referenced this way to make the point that they are destination places. This means that these are places were one sets out to go, and do not depend primarily on heavy pedestrian flow. Therefore, these can well be banks, pharmacies, dentist office or other services of the sort. Contrastingly, the “retail stores” (brown colour) depend more on casual passers-by and given the chance, will attempt to attract them.

2013

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Figure 5.4: Pedestrian flows on site with the changes for 2015 and the proposal.

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Pedestrian streets Bike path Underground system Train station Hotels Gastronomy Grocery stores Shopping centres Theaters Private education Public education Office towers on site Retail stores

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Figure 5.5: Plan showing different activities on site and within a 5 minute walk radius (500 metres).

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5.4 Density The pie chart in Figure 5.6 gives the programmatic proportions considering the project. The 125.000 m² added in the proposal would account for 20% of the future scenario. Most of this addition is housing. This offers a unique opportunity for inserting segregated parts of the community. Hence, 10% of the new scheme is suggested as social housing. Additionally, another 20% is planned as amenities articulating the ground floor. These three layers may be identified in the image of Figure 5.7.

Furthermore, the spaces enclosed are considered as “particular” given their solar availability. These are spaces that receive sun during at least one of the time frames where sun is desirable in terms of thermal comfort. This is the reason why the buildings were placed as walls enclosing these spaces. In addition, the density was moved in order to obstruct as little as possible the solar radiation while at the same time meeting the high density of the consolidated tissue. This was fulfilled maintaining the target density following the strategies shown in Figure 5.8.

The dates shown in the image which influenced the design are June 21st, which is the winter solstice, and September 15th. The latter denotes the beginning of the last quarter of the cool period, which is homologous to the last day of the first quarter. This implies that an area that receives sun at this moment will receive sun throughout the first and last quarters of the cool period, making up for half of the interlude. This criterion was followed for the morning and afternoon time frames, when solar radiation is considerably weak.

Furthermore, the insertion of the project on site filling the gaps between the consolidated grid and the towers may be seen in Figure 5.9.

In addition, the image shows how the height of the buildings projected was calibrated forming a relationship with the Spanish grid. The effect of all these operations can be further seen in the images of Figure 5.10 on the following pages. The project viewed from above with the midday sun of the summer solstice is here displayed. Additionally, the sun path diagram for six points and their corresponding sun paths have been plotted. These points represent different spaces which were enclosed or given character by the proposed buildings.

In point one, it can be identified that solar availability during the studied time frames is severely restricted throughout the cool period.

However, one can also note, that this area has good solar accessibility most of the year. This may be exploited in off hours by the occupiers of the residences surrounding it. Moreover, in the second example one can see how the density move enhances solar availability for the morning hours. Additionally this area has good solar potential during the midday time frame throughout the year. The horse shoe shape of this space gives it a strong semi-public character which will grant a protection from the city to the users of this space. Points 4 and 5 show how density was moved to foster solar availability during the midday time frame. These spaces are gradually more opened to the rest of the city. The last two points are not delimited by the buildings. The first is an open area which has the rare advantage of receiving sun during the late hours of the day even in the cool period. The second exploits this same advantage from the sunken point of an auditorium. In turn, this auditorium is projected as a shared space between the three towers which border it.

Finally, what the proposal is offering is an array of different spaces which offer very different opportunities. At the same time, all these spaces except point 5 have a semi-public character to encourage the sense of belonging. Nevertheless, although point 5 has a more public character, it has a calibrated size, which will encourage activity development. In addition, the calculations for percentage of hours of sun during the nine different time frames with the proposal may be found in appendix I. 54

Offices 49.000 m²

(72%)

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Proposal

Figure 5.6: Programmatic proportions considering the project.

MArch Sustainable Environmental Design 2011 - 2013

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Figure 5.7: Programmatic breakdown of the project.

June 21st 12:00

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June 21st 12:00 Added density to meet the avenue Cordoba.

Septemeber 15th 8:00

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All potentially useful sun is blocked by the surrounding buildings, hence, density is added.

Density is added to address the high density of the consolidated tissue

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Figure 5.8: Densification strategy of the project

Figure 5.9: CGI showing the insertion of the project in the city 55

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Point 01

Point 02

Space which had the solar availability hindered in the specific time frames by context.

Plot oriented primarily to the morning time frame.

However, it does receive a substantial amount of sun throughout the year.

Most of it receives sun during the midday time frame as well

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Courtyard oriented primarily to the midday time frame

Figure 5.10: CGI of the project viewed from above with the sunpath diagrams for 6 representative points.

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Point 04

Space oriented primarily to the midday time frame

Point 05

Plaza oriented primarily to the midday time frame It was recessed in order to receive sun during the afternoon period as well

Architectural Association School of Architecture

Point 06

Auditorium oriented primarily to the afternoon time frame.

However, most of it is exposed during the midday time frame

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m/s > 5.0 5.0 4.0 3.0 2.0 1.0 0.5

5.5 Assessing the wind environment

It had been identified in the previous section that high air speeds on site presented an important disadvantage. The mitigation of this effect was another argument for calibrating the enclosure of the different spaces.

Therefore, wind simulations have been carried out with the insertion of the project. These were performed in order to understand how the structures proposed altered wind patterns. The inputs for the simulation were the same as for the previous studies.

The results of the simulation for the three predominant wind directions presented in Figure 5.11 show two things. The extensive nature of the project occupying the ground floor reduces overall air speeds.

Additionally, the enclosed areas offer considerable wind protection most of the time. The analytic work carried out for outdoor thermal comfort proves this to be an advantage.

Additionally, Figure 5.12 offers a comparison of the scenarios for 2012, 2015 and the projected setting. The added density for 2015 is of slightly more than 160.000 m², which is 25% more than the density projected in the proposal. Nevertheless, the three new towers have little impact upon wind patterns. They do lower air speeds, but offer seldom new protection. However, when studying the protections offered by the proposal one may see how an adverse situation may be reverted.

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Always with high air speeds (above 3 m/s) Always with low air speeds (below 3 m/s)

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90째

Figure 5.11: CFD simulations for the predominant wind directions on site with proposal

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Figure 5.12: Comparison of protected and exposed areas with the three scenarios

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One of the first studies carried out on site consisted on calculating the percentage of hours of sunlight available on site for the different periods.

This study is here presented in Figure 5.14. Upon a closer look, one may identify that the most important shading on site over the nine time frames is inherent to the setting.

Afternoon time frame

Midday time frame

Additionally, the calculations for the diffused component during the nine time frames have been carried out. These may be found in Appendix.

The findings from these show what has been identified before, that there is a strong correlation between the diffused component and the sky view factor. Therefore, throughout the different periods and time frames, the areas which are most obstructed have always the lowest values.

Morning time frame

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Figure 5.13: Key map showing area of focus

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Cool Period

Figure 5.14: Study of direct solar availability on site within the different time frames.

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5.7 Visual Connections Despite the fact that the area in question does present issues in terms of solar availability, sun is frequently available in one space or another at any given moment of the time frames studied. This encourages further adaptation. Figures 5.16 and 5.17 show the sky view factor with the sun path overlaid taken from two representative points identified in the plan of Figure 5.15. The former image shows that there is sun availability for the morning time frame throughout the year, while the latter shows good solar prospects for the midday time frame.

What has the potential of making this area successful is the strong visual connection between the two points. This would allow a user of the space to move from one area to another in search of sun or shade. As specified before, it is not one combination of solar radiation and air speed that makes for a successful space, but the offer of many within a walking distance.

Figure 5.15: Plan of area of focus

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Barrier Delimits public from semi private space

Public “secondary seating” It is a seating opportunity that does not give a sensation of empty when it is not used. (gehl 2010)

Figure 5.16: Sunpath diagram for point “A”

Evergreen trees As sun angles are low in the morning, solar radiation would only be blocked during the midday time frames. During these, it is not available in these areas throughout the cool period

Deciduous trees.

Cleared branches will enable solar radiation to go through during the midday time frames.

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Figure 5.17: Sunpath diagram for point “B”

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5.8 Dealing with the wind at a pedestrian level It was consistently found in the literature that wind speeds of 5 m/s or above were not tolerated by people involved in sedentary activities for long periods of time (Nikolopoulou, 2002). Furthermore, it has been identified that the morphology of the surrounding structures already provides some degree of protection. Nevertheless, it was identified by a more focused evaluation that further protection was needed.

This focused evaluation consisted on simulation analysis with smaller cell boxes (2 x 2 x 2) which allowed for more details to be perceived.

CFD Simulations were carried out for every 30°, and the most problematic results are here presented in Figure 5.18. These are considered problematic based on the frequency of occurrence and the overall simulation results.

The remaining simulations may be found in the appendix.

It was detected that wind was accelerated by the downdraft effect created by the circular tower. This effect needed to be mitigated.

However, an array of different moderate air speeds within the site would be considered as a quality as they would offer more options.

m/s > 5.0 5.0 4.0 3.0 2.0 1.0 0.5

Furthermore, in order to mitigate these effects, a pergola working as a barrier has been designed for the cylindrical tower. It was recreated as solid for the simulations presented in Figure 5.20. However, field studies have found that barriers with a 35-40% opening area perform better (Nikolopoulou, 2002). The pergola shown in Figure 5.19 has a 40% opening area. Additionally, a second pergola was designed for the proposed buildings. As a result, wind overlaps the hotel, is pushed down by the tower, and then jumps from one pergola to the other. Therefore, most of turbulence is kept separated from the pedestrians.

Wind (direction = 0°)

Wind (direction = 30°)

Wind (direction = 60°)

Wind (direction = 210°)

Wind (direction = 240°)

Wind (direction = 330°)

Figure 5.18: CFD simulations performed on the focused site before Intervention

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Figure 5.19: CGI showing pergola working as a wind barrier

Wind (direction = 0°)

Wind (direction = 30°)

Wind (direction = 60°)

Wind (direction = 210°)

Wind (direction = 240°)

Wind (direction = 330°)

Figure 5.20: CFD simulations performed on the focused site after Intervention

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For the reasons presented previously, a strong visual connection with the opening to the west was desired. However, openings within buildings tend to accelerate air speeds in the surrounding areas. As explained before, this could not be allowed to happen. Therefore, the visual connection was placed where the building has the lowest height as seen in Figure 5.21.

This way a minimum of wind is blocked, and the resulting wind pushed downward is reduced. All simulations have been run with this connection.

Concluding, it needs to be stated that air movement does not necessarily present a problem always. As a matter of fact air movement has many benefits such as dispersing pollutants. Nevertheless, when attempting to encourage sedentary activities, high air speeds should be reduced.

Visual Connection

Figure 5.21: CGI showing visual connection between spaces where the building is lowest so as to mitigate wind effects.

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Vantage point

Figure 5.22: CGI showing the vantage point for the following images on October 6th at 12:30.

5.9 On site Performance Assessment

Diffused component

Direct component

Comfort graphs

The following nine figures are here given to illustrate the performance on the site throughout the nine time frames discussed concluding the chapter.

In each figure, a key map is given referencing three points. The same three points are taken throughout the examples. The wind simulation used is the one corresponding to the predominant wind direction identified in the time frame analysis (chapter 2).

The diffused component was calculated through the use of Ecotect Analysis 2011. All nine time frames have been analysed this way and the results are displayed together in the appendix.

In order to assess the degree of sun availability, the calculations showed previously of solar availability have been used. Additionally, the intensity of the direct solar radiation was the one found at least 50% of the time for the given period. These frequency graphs have been taken from the previous time frame analyses (chapter 2).

Finally, each point has been plotted into the corresponding comfort graph for the given period. These have been taken from the analytic work (chapter 3). Therefore, for any given point one may understand which percentage of the time frame it will offer highly comfortable conditions for pedestrians. In addition it will begin to discern pedestrian patterns of choice.

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Figure 5.23: CGI for a typical summer morning (December 21) showing a reduced number of people on the streets given the typical summer break. People will tend to look for sunny patches to sit oneself down.

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Figure 5.24: CGI for a typical summer midday (December 21st). People will tend to look for comfort in shaded areas.

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Warm period Afternoon time frame

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Figure 5.25: CGI for a typical summer afternoon (December 21st). People would seek comfort in shaded and protected areas.

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Mild period Morning time frame

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Figure 5.26: CGI for a typical spring morning (September 21st). There would be typically more people in the streets. People would seek sunny patches, and wind protection is essential.

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Mild period Midday time frame

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Figure 5.27: CGI for a typical spring midday (September 21st). Sun exposure is not essential for thermal comfort but could provide quality.

However, if one is exposed, more air movement will also be required.

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Mild period Afternoon time frame

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Figure 5.28: CGI for a typical spring afternoon (September 21st). Sun exposure becomes a high comodity. However, wind protection is essential for any sedentary activity to develop outdoors within this time frame.

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Cool period Morning time frame

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Figure 5.29: CGI for a typical winter morning (June 21st). Sun exposure is not essential for thermal comfort as it is too weak However, as long as there is wind protection, on a good day, people could be inclined to sit, but for shorter periods of time.

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Cool period Midday time frame

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Figure 5.30: CGI for a typical winter midday (June 21st). Less people would go out looking for food than on a midday of the mild period, prefering the higher indoor air temperatures. Nevertheless, those who do go out would value the opportunity of being outoors, lowering their comfort expectations.

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Cool period Afternoon time frame

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Wind (direction = 180°)

Difused solar radiation

m/s

W/m² 75+

52.5

30

7.5

2.0

67.5

45

22.5

0

1.0

60

37.5

15

> 5.0

3.0

5.0 4.0

0.5

1 metres per second

0W

3 metres per second

0W

2 metres per second

0W

MArch Sustainable Environmental Design 2011 - 2013

Exposed to direct sun

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Intensity of direct solar radiation

Comfort graph

% of hours 100

60

30

60-70%

30-40%

80

50

20

50-60%

20-30%

70

40

0

40-50%

10-20%

0-10 %

W/m²

%

200

100 90 80 70 60

100

50 40 30 20 10

50

100 150 W/m²

Protected from direct

0W

Exposed to direct

0W

Protected from direct

0W

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250

1

2

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5

50

Figure 5.31: CGI for a typical winter afternoon (June 21st). People are more likely to rush home than to stay about the area. However, those who do stay will seek out wind protection. Overall, people are more inclined to withstand lower temperatures when they are drinking something rather than when they are eating. This is mainly because of the time lapse for one activity and the other.

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Chapter 5: Design Application

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5.10 Discussion It is understood by the author that the 60 metre avenue is one main traffic artery for the city of Buenos Aires. Clotting it would certainly cause numerous problems to the city in terms of connectivity. However, creating 125.000 m² of built area would certainly create important profits. At this point two options are possible. For one, the revenues could be used to create an underground motorway attempting to maintain the current city flows. A second option would be to undertake a holistic approach of using these revenues to improve the whole public transport system. The author strongly encourages the latter. However, the exploration of these options is beyond the grasp of this dissertation.

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Conclusion

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City as environment for man

Outdoor spaces are what articulate city life. It is the spaces between buildings which connect one building with the other. Moreover, it was concluded in this dissertation that understanding when these connections happen becomes a critical factor for providing favourable conditions for pedestrians.

The symbiotic relationship

lack of recognition

Lessons

recognition

The city of Buenos Aires provided a setting for this dissertation, and it was found that the overall good climatic conditions present positive prospects for pedestrian thermal comfort. However, outdoor spaces are strongly linked to the buildings which border them and can turn advantageous scenarios into detrimental ones. Therefore, a symbiotic relationship between buildings and outdoor spaces can be identified.

An ill performing pocket of the city has been chosen to test the hypothesis here presented. The poor offer of adaptive opportunities in terms of thermal comfort and the lack of programmatic variety within the site where two of the main issues identified. These issues are symptoms of a lack of acknowledgement from behalf of the buildings towards that symbiotic relationship. In addition, the 60 metre wide motorway limited opportunities for pedestrians. The combination of these factors results in a limited pedestrian flow within the site. Additionally, an investigation was carried out to assess the impact of the future structures to be built on site, showing no significant change.

Alternatively the Spanish grid has been assessed. The limited lot widths along with the narrow streets have been found to be positive factors for stimulating city life. Moreover, in terms of solar radiation it was concluded that the incidence of canyon orientation on direct solar availability is stronger as density is higher.

Nevertheless, amid the design proposal, it is argued in this dissertation that through sensible planning buildings could enhance and revitalize the open spaces that surround them. An array of different conditions has been offered to pedestrians within short walking distances, encouraging adaptive thermal comfort. Additionally, the insertion of housing and restaurants couples these new opportunities with a programmatic variety.

It is further claimed, that these two concepts together will be able to alter existing pedestrian flows, resulting in a new vitality within the site.

These strategies will effectively integrate this neglected city space with the consolidated urban tissue, proving the research hypothesis to be assertive.

The symbiotic relationship between buildings and outdoor spaces has been broadly discussed. However, just as buildings affect outdoor spaces, the latter affect pedestrians or city inhabitants. Hence, a new symbiotic relationship is identified between cities and citizens. The character of the former will ultimately alter the way the latter uses the spaces provided.

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Appendix

Morning time frame %

70 60 50 40 30

Midday time frame

80

a. 1 Assessment of direct solar radiation The study on the percentage of hours within the different periods where solar radiation is available within the project here shown in Figure a.1. It expresses the intention of the buildings to encircle areas which receive the most solar radiation within these time frames. In addition, one can see the attempt of blocking as little direct solar radiation as possible.

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Afternoon time frame

20

Appendix

Warm Period

Mild Period

Cool Period

Figure a.1: Assessment of percentage of hours when direct solar radiation is available in the site with the inclusion of the project.

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Appendix

After Intervention

Before Intervention

a.2 Wind simulations before and after intervention

100

Wind (direction = 0°)

Wind (direction = 30°)

Wind (direction = 60°)

Wind (direction = 90°)

Wind (direction = 120°)

Wind (direction = 150°)

Wind (direction = 0°)

Wind (direction = 30°)

Wind (direction = 60°)

Appendix

Wind (direction = 180°)

Wind (direction = 270°)

Wind (direction = 210°)

Wind (direction = 210°)

Wind (direction = 300°)

Wind (direction = 240°)

Wind (direction = 240°)

Wind (direction = 330°)

Wind (direction = 330°)

Figure a.2: Wind simulations for focused site before and after the intervention.

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Appendix

Morning time frame

W/m² 250+

100

225

75

200

50

175

25

150

0

125

Midday time frame

W/m² 350+

170

320

140

290

110

260

80

230

50

200

a. 3 Assessment of diffused solar radiation for the area of focus

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W/m²

Afternoon time frame

Given that for the simulations the albedo for all materials was kept the same for sake of simplicity, the diffused component has a straight direction with the sky view factor for the different areas. Therefore, it is argued that although intensities change with date and time, the intensity within a specific site only varies proportionally. Consequently, areas which receive lower values of diffused component during the warm period receive the same proportion of low levels during the mild or cool period.

75+

30

67.5

22.5

60

15

52.5

7.5

45

0

37.5

Appendix

Warm Period

Mild Period

Cool Period

Figure a.3: Diffused solar radiation assessment within the focused area.

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